X 



ORE MILLING 
MACHINERY 


CATALOGUE NO. IO C 


1560 1912 

DENVER, COLORADO 

U.S.A. 





























































Catalogue No. 10-C. 


Advanced Cyanide Practice 

and Equipment 

Being a Brief Description of the Cyanide Process 
and of Equipment Used Therein 


Copyright 1912 by Colorado Iron Works Co. 


Colorado Iron Works Co. 

Denver, Colorado, U. S. A. 

9 


» J 
) > » 


Private Exchange Telephone, Main 3380 

Cable Address: “Nesmith, Denver.” Codes: Lieber’s, Bedford McNeill’s, 
Moreing & Neal's, A. B. C. (fifth edition), Western Union, Directory. 





C Cl, A 316 6 6 5 


PLANT OF COLORADO IRON WORKS COMPANY. 













ANNOUNCEMENT. 


The purpose of this book is to acquaint our friends and the public 
with certain machinery which we build for use in cvaniding ores. 

u i o 

The equipment shown is limited to that having special interest to 
cyanide process operators, and we shall issue a separate catalogue 
covering crushing, screening and other machinery of general appli¬ 
cation in all processes of ore reduction. The catalogue is preceded 
by a short description of the cyanide process, which it is hoped will 
prove useful to those who are not informed in its theory and appli¬ 
cation. 

In many cases cyanidation is combined with amalgamation or 
concentration, or both. On each of these processes we issue a separate 
catalogue, as well as one on smelting; any of which will be mailed 
on application. 

A great many plans of mills and smelters are on file in our 
engineering department, which will prove of great service to those 
planning the erection of ore treatment plants, and we employ a large 
corps of engineers and metallurgists of wide experience, whose assist¬ 
ance is at their command. 1STo charge is made for ordinary service of 
this kind, but, where expense is involved, the work will not be under¬ 
taken without a previous understanding. 

We design and equip plants for the reduction of ores by all mod¬ 
ern processes and in addition we will engage to erect them complete, 
demonstrating their efficiency in practical operation. 

We endeavor to have our illustrations correctly represent the 
various machinery, but in the advance which is continually being 
made in efforts to improve it, changes in detail are made from time 
to time. As these are in the interest of the purchaser, we feel that 
an apology on this account is perhaps superfluous. 

Our aim has always been the production of a high-grade line of 
machinery, the prices being made as low as consistent with high 
quality. In no case do we attempt to build a machine to come within 
a certain price and place it in the field of competition with others 
having low first cost as their chief merit. It is this policy, consis¬ 
tently maintained for fifty years, that has established our enviable 
reputation. 

COLORADO IR0IS T WORKS COMPANY. 



4 


OUR FACILITIES, TERMS, ETC. 


COLORADO 

IRON WORKS CO 


REPAIR WORK. 

We desire to call particular attention to the promptness with 
which repairs and renewals can be made at our works. Our foundry 
and machine shops are ample and no delays need be anticipated. 

Our advantages are apparent to our milling friends in the Rocky 
Mountains, as from three to fourteen days are saved in procuring 
supplies from Denver direct. We have telephone connection with 
nearly all mining camps in Colorado and adjoining States, and prefer¬ 
ence is always given renewal orders, as we fully realize the importance 
of keeping a mill running. 

In ordering repairs be very specific and give numbers where 
possible. Make measurements carefully, and when possible give a 
rough sketch, no matter how crude. Where practicable refer to cata¬ 
logue number for details, etc. 


TERMS. 

Our terms to regular customers with established credit are 
monthly settlements. On new business, for equipment only, one-third 
to one-half cash with order, balance when ready for shipment. On 
new business, for equipment and erection, one-third to one-half cash 
with order with special arrangements as to payment of the balance. 
On special work done to order, cash in advance or part cash in advance 
and an ample guarantee to secure payment of the balance. 

Remittances should be in Denver or Rew York funds or their 
equivalent. We pay no exchange. 

SHIPPING DIRECTIONS. 

Shipping directions should be explicit and state whether by 
freight or express. If not otherwise instructed, all material will be 
shipped by freight, except light packages, which will be forwarded 
by express. 

Our responsibility ceases with delivery to the carrier in good 
order. In the event of loss or damage in transit, the agent of the 

LA 7 0 

carrier should be immediately notified. We will render all assistance 
possible in adjusting the claims of our customers for losses, damage 
and excess charges. 


COLORADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


5 


The Cyanide Process. 

The solubility of gold in solutions of the alkali cyanides had 
long been known; but as the experiments had been with compara¬ 
tively strong solutions, the facts were of only scientific interest, as it 
seemed that the cost, instability and poisonous properties of the cyan¬ 
ides would prevent their use in a process of extraction from ores. It 
was comparatively recently that attention was directed to the appli¬ 
cation of potassium cyanide direct to gold ores and, as is usually 
the case with new processes, the methods proposed were more compli¬ 
cated than were later found to be best. 

After it had been demonstrated that gold in ores could economic- 
ally be brought into solution as a double cyanide of gold and potas¬ 
sium, an efficient means of precipitation was still lacking to complete 
a working process. A number of investigators deserve great credit 
for early work in this line, but for the cyanide process as we know it 
todav the world is indebted to J. S. Mac Arthur, R. AY. Forrest and 
AY. Forrest. These men carried out a very exhaustive series of re- 
searches, as a result of which they presented a complete and acceptable 
working process, one of the most important features of which was the 
recovery by precipitation with zinc shavings. A discovery made by 
them, and for which much was claimed, was that a very weak solution 
of potassium cyanide exhibited a selective action, by which the gold 
and silver went into solution and the base metals remained unaffected. 
Considerations affecting the time of treatment and general economy 
of actual operation prevent the use of solutions of such strength as 
to take full advantage of this property, but the interference from 
objectionable constituents is slight notwithstanding; much less, for 
example, than the effect of such compounds in the application of the 
chlorination process. 

The work of MacArthur and the Forrests was so thorough and 
complete from a technical standpoint that it may fairly be said that 
the improvements which were made during many years subsequent 
to the time when their process was first introduced on the Rand in 
1891, have been very largely of a mechanical and engineering nature. 
It must not be inferred from this that the art is remaining station¬ 
ary. This is very far from the case as the advancements made in 


6 


THE CYANIDE PROCESS. 


COLORADO 

IRON WORKS CO 


methods of handling the material and in the control of the process 
have made it much more attractive than it was even two or three 
years ago. The present tendency is toward the development of con¬ 
tinuous treatment methods with the elimination of all manual labor 
and the removal, to a large degree, of “the personal equation”. The 
ultimate goal is the attainment of a practically automatic, continu¬ 
ous method, using the principle of counter-currents in which the 
flow of the solution is contrary to the flow of the ore; and this may 
be said to be now at hand. 

It is agreed that the gold goes into solution as a double cyanide 

O o o 

of gold and potassium, in the form expressed by AuK(CF) 2 , and 
although some authorities have disputed the necessity of the presence 
of oxygen, it is almost universally admitted that oxygen or an oxidiz¬ 
ing agent is essential. Conversely, reducing agents exert an injuri¬ 
ous action, and their presence is to be avoided as far as possible. For 
these reasons it is attempted in practice to secure a thorough oxygena¬ 
tion during treatment and to avoid the unnecessary formation of com¬ 
pounds having a reducing action as well as to add suitable reagents 
to counteract their effect when unavoidably present to such an extent 
as excessively to destroy cyanide. 

The selective action of cyanide solutions is at its maximum in 
solutions of greater dilution than are found most economical in regu¬ 
lar working, but, fortunately, great solvent effect is exerted by small 
concentrations and the cost of cyanide per ton of ore treated is there¬ 
fore low. 

The more important early applications of the cyanide process 
on a large scale were to the treatment of accumulations of tailings, 
from which it was readily extended to tailings from the current pro¬ 
duction of mills. The process has now, however, taken a place in the 
very front rank for direct application to ores, although in many cases 
in connection with amalgamation or concentration. The ores amen¬ 
able to cyanidation are of very common occurrence, and with by far 
the greater number no preparation, other than crushing, is required. 
The exceptions are telluride and sulphide ores, either in which the 
precious metals are not soluble in cyanide solutions or in which the 
deleterious action of the objectionable constituents would cause a too 
great loss of cyanide. The remedy is preliminary roasting, or treat¬ 
ment in the wet way by means of oxidizing agents applied in soln- 


COLORADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


tion. Owing to the excessive cost of roasting, the chemical oxidation 
of such ores has recently been given great attention and the entire 

d O o 

satisfaction with which such treatment is being carried out in a num- 
ber of recently completed plants has demonstrated the success of the 
method and warrants its general acceptance. Concentration is often 
advantageously combined with such a method, as by this means the 
greater part of the sulphides is removed, the small portion remaining 
being economically treated bv oxidizing agents in solution and a 

O d d o o 

shipping product of concentrates being obtained as well. 

During the last few years the use of the cyanide process has been 
extended to purely silver ores, many of which are now treated en¬ 
tirely by cyanidation with a greater saving than possible by any 
other method. The process for silver ores is essentially the same as 
for gold ores, the principal difference being in the increased time 
required for solution of the silver. The purpose in hand will there¬ 
fore be served by a description of the cyanide process in its appli¬ 
cation to gold ores, the various steps in which will be outlined in 
their regular order. 

o 

T. Preparation of the Ore. 


It is essential that the particles of gold be sufficiently freed from 
the surrounding gangue for tlie cyanide solution to reach and dissolve 
them, but any further comminution is unnecessary and may even be 
undesirable. The condition of the gold in the ore, therefore, governs 
the degree of fineness of crushing, and it may be stated here, although 
it applies with corresponding force to every step in the process, that 
it is not possible to obtain total extraction 5 that to recover the last 
remaining portion of the gold involves a cost far in excess of its 
value, and that the attempt should be to attain that degree of extrac¬ 
tion which, all things considered, will return the greatest profit in 
dollars and cents. 


r T n fil recently the most economical method consisted in crush- 
im>’ the ore sufficiently to liberate the gold, leaching the coarse sands 

d _ 

in tanks and treating the slimes separately. The controlling factor 
was the expense of treating the slimes, hence the effort was to crush 
in such a way as to make a minimum of extremely fine material. 
Improved equipment for agitation, slime thickening and filtration 
has placed the treatment of slimes on a different basis and they are 


8 


THE CYANIDE PliOCESS. 


COLOR ADO 

IRON WORKS CO 


not only no longer dreaded, but the newer methods consist in crush¬ 
ing the entire ore to what is practically an all slime product, thereby 
treating the whole ore by one method. Inasmuch as sand leaching is 
still used to a large extent and will continue to find application in 
special cases, it will be well to describe it in some detail. 

The degree of fineness nsed in practice varies from about one- 
half inch down, with 20 or 30 mesh as common. Machinery of all 
types nsed in crushing ores for treatment by other processes finds 
application in cyanidation, and the same effort is made to reduce 
all the ore to a certain size without the production of an excessive 
amount of slimes. 

Either wet or dry crushing is adopted, the choice depending 
upon the nature of the ore. If crushed dry, the cyanide solution 
comes immediately into intimate contact with the ore, but the solu¬ 
ble acids remain in the ore and cause a loss of cyanide. On the 
other hand, if crushed wet, the soluble acids are washed out, but 
there is a dilution of the solution by reason of the moisture retained 
bv the ore and the action of the solution when applied is more or 
less delayed. Many ores show no difference in cyanide consumption, 
whether crushed wet or dry, but others if crushed dry consume such 
an excessive quantity of cyanide that washing must be resorted to 
before the application of the cyanide solution. It is obvious that 
ores of this kind should be crushed wet, which will accomplish the 
washing in the same operation. 

In crushing an ore, it is always most economical to make a 
product containing a proportion of particles larger than the desired 
maximum and to separate this oversize and return it for recrushing. 
If an attempt is made to crush all sufficiently fine to at once pass a 
screen of the desired mesh, a large amount of slimes will be pro¬ 
duced and the cost of crushing will be greater. For both wet and 
dry crushing, the highest type of rolls have no superior. When 
amalgamation is used, stamps give the best results. For regrinding 
the product of either rolls or stamps to sizes not economically attained 
in one operation, use is made of Chilean mills and others of similar 
type. 

For dry crushing, the ore must first be dried, which is a point 
to be considered, and the relative amount of dust and slimes pro¬ 
duced in dry and wet crushing also should influence the choice of 


COLORADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


9 


methods. In general the quantity of dust made in dry crushing is 
less than the amount of slimes produced in crushing the same ore Avet, 
hut the assay value of the dust is usually higher than that of the 
slimes. 

The crushed ore should he systematically sampled and an accu¬ 
rate record kept in order to provide a check on extraction. It is 



SIXTY-STAMP MILL CRUSHING IN CYANIDE SOLUTION. 


only by strict attention to the weight of ore, strength of solution and 
time of treatment, in connection with assays of the ore, tailings and 
solutions, that a check can he kept on operations and the extraction 
improved wherever possible. 

II. Dissolution of the Gold and Silver. 

Ores vary greatly with respect to their leaching qualities, some, 
although finely crushed, being more permeable than others less finely 
reduced. Sands will carry a certain proportion of slimes, if uni¬ 
formly mixed, and still be suitable for treatment by leaching and 
percolation and some plants are so fortunate as to handle an ore 
all of which forms a teachable product, although in most cases it is 
necessary to separate the slimes for special treatment. W hen the 








10 


THE CYANIDE PROCESS. 


COLOR ADO 

IRON WORKS CO 


attempt is made to leach a pulp containing an excessive amount of 
slimes, channels will form in it and the solution will follow these 
comparatively unobstructed paths instead of percolating evenly 
through the whole mass, thus entirely defeating the purpose of the 
operation. 

The treatment of sands by percolation and leaching is conducted 
in tanks. The features of these tanks which are special to cyaniding 
purposes, consist principally in the filter bottoms and gates for dis¬ 
charging the sands after treatment. They may also be provided with 
automatic devices for filling; them with the crushed ore. M in or dif- 

o 

ferences exist in filter bottoms, but the essential features are a grating 
laid upon the bottom of the tank, a layer of cocoa matting upon the 
grating and a cover of canvass, the latter being caulked around the 
periphery of the tank and around the discharge gates with rope. In 
some cases a layer of clean sand is placed upon the canvas and allowed 
to remain, a grating being sometimes placed a short distance above 
the canvas to form a guide in shoveling; but this laver of sand can. 
of course, only be made use of where tanks are emptied by shoveling, 
and not where the contents of the tanks are hosed out, which is the 
usual method in this country. 

t/ 


T1 le solutions are drawn from a pipe entering the tank below 
the filter bottom, the grating being notched in such a manner as to 
permit a free flow of the solution to the outlet. Gravity is usually 
sufficient for percolation, although in some instances a vacuum is 
maintained below the filter and the operation is sometimes conducted 
in pressure tanks, although either of these is very exceptional. 

The discharge of the sands is through gates in the bottom or 
doors on the side of the tanks into sluices through which the tail- 
ings are run to waste. In some cases, however, the tailings cannot 
thus easily be disposed of and have to be stacked, involving special 
equipment for their disposal. 

The number of tanks to be supplied for a given capacity depends 
upon the time required for dissolution. Their depth depends upon 
the leaching qualities of the pulp to be treated. Experiment will in¬ 
dicate the depth of the column of pulp through which the solution will 
percolate at a satisfactory rate, three inches per hour being good, 
and one and one-half inches per hour fair. The depth of the tanks 
being established in this manner, their diameters are made sufficient 


COLORADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


11 


for the required capacity, good practice being to make them of such 
size that one or a definite number will hold a day’s run, thus secur¬ 
ing evenness in operation by performing the various steps of filling, 
emptying, etc., at a certain time each day. 

Not only the specific gravity of the pulp, but the manner of 
charging the tanks greatly influences the capacity in tons of sand. 
If crushed and charged dry the weight will be fairly constant, as 
will also be the case if crushed and sized wet and charged direct. 



SAND LEACHING TANKS IN CYANIDE PLANT. 


If crushed wet, dewatered and charged moist the proportion of weight 
to bulk will vary between wide limits. Dry pulp is taken to the 
tanks by cars or conveyors passing over them, dumped, and spread 
out by hand shoveling. When wet crushed pulp is charged direct, it 
is led to an automatic distributor which spreads it evenly, and this 
forms an ideal method of filling. 


The tank being filled, the first operation, if charged wet, is to 
drain it, which is done by opening the valve communicating with the 
space below the filter bottom. After draining, the solution is run on 
the top of the charge or is let in below the filter bottom. In the 
latter case it is usually allowed to rise to the surface of the pulp and 

t/ 













12 


THE CYANIDE PROCESS. 


COLORADO 

IRON WORKS CO 


the rest of the solution then added. Practice varies in the way the 
solution is applied, but as almost any method may he followed with¬ 
out change in the plant, the most suitable one may easily be worked 
out when the plant is put in operation. The principal variations 
concern the strength of the various solutions employed and the 
amount added at one time, as well as the extent to which the wash¬ 
ing is carried. 

In downward percolation, it is usual to apply a sufficient quan¬ 
tity of solution to displace the previous solution, as soon as the latter 
has sunk below the surface of the pulp. The solution last added will 
then follow the previous one down through the ore without mixing 
with it to any appreciable extent, the level of the solution indicat¬ 
ing the time at which the new solution appears in the discharge. 
In this way the time is known when, instead of sending the solu- 
tion to the gold tank for precipitation, it should be run to a sump 
for reuse until the value is brought up to a sufficient amount for 
precipitation. This is continous leaching, in which percolation is 
carried out by the displacement of one solution by the one following. 
In some instances it has been found that better results can be ob¬ 
tained by intermittent treatment, in which the tank of pulp is allowed 
to drain completely between the different applications of solutions 
and wash water, this is probably due to the aeration of the pulp by 
the air coming into contact with it. 

The extent to which the washing should be carried can also be 
worked out when the plant is in operation. It is always better to add 
a large number of small charges than a small number of large ones. 
The first two or three washes very greatly reduce the value left in 
the pulp and succeeding ones remove comparatively little, as the last 
remaining values, although they may be in solution, are retained very 
tenaciously. 

The salt, potassium cyanide, varies in purity, and different 
grades are designated bv the percentage of pure salt contained. Thus 
98 per cent, potassium cyanide contains 2 per cent, of impurities. 
Sodium, having a lower atomic weight than potassium, has a greater 
saturating power for other elements. This has led manufacturers to 
label sodium cyanide in terms of its equivalent in potassium cyanide, 
giving rise to such expressions as “130 per cent, cyanide.” These 
points should not be lost sight of in purchasing cyanide for the fol- 


COLORADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


1 Q 


O 


lowing reasons: The impurities present in cyanides are not inert, 
but consist largely of sulphides and other detrimental compounds. 
All commercial potassium cyanide contains more or less sodium cyan¬ 
ide, and if a large amount of impurities are present, the sodium 
cyanide present will, if in sufficient quantity and expressed in terms 
of potassium cyanide, give a percentage figure indicating a high 
degree of purity. The strength of solutions used in cyaniding is 
expressed in pounds per ton of water, a “five-pound solution” mean¬ 
ing one containing five pounds of the solid salt in one ton of water. 
For the best results, the amount of cyanide used should be as low as 
possible and still leave a slight excess to facilitate precipitation. 
The actual amount used varies so greatly that definite figures can¬ 
not be given, but it is generally very small. 

If the pulp produced contains an excess amount of very tine 
material it cannot be treated by percolation, and the slimes must be 
separated and handled by special methods. The separation of sands 

from slimes is best effected by means 
of mechanical classifiers, which are in 
every way superior to hydraulic cones, 
spitzkiisten and similar devices. 

The slimes separated by the classi¬ 
fiers carrv a large amount of water, 
or solution if crushed in cyanide, and 
it is necessary that the excess be re- 
moved in order that the moisture 
carried by the slimes will not greatlv 
dilute the solution when applied. 
Th is thickening is accomplished in 
thickening tanks, which may be sim¬ 
ple cone bottom tanks but preferably 
special thickeners, having a large set¬ 
tling area with rakes in the bottom to 
move the thickened product to a con¬ 
veniently located cone from whence 
they may be drawn continuously. 

The treatment of slime is by agi¬ 
tation in a solution of suitable 
strength, for a time dependent upon the rate of dissolution. I lie 
method of agitation now almost exclusively used is by circulation, 
using centrifugal pumps or an air lift within a tall tank. The an¬ 
nexed illustration is reproduced from our catalogue, number 10-A, 















































14 


THE CYANIDE PROCESS. 


COLORADO 

IRON WORKS CO 


published in 1905, and represents what is now in general use with a 
few minor changes, under the name of the “Pachuca” tank. 

Pecent important patented improvements in agitation tanks are 
provisions for starting after the slime may have settled hard from 
the tank being temporarily out of operation; for continuously with¬ 
drawing pulp from the tank, the part so withdrawn being of the same 
physical condition as the contents of the tank, thus preventing the 
accumulation of sands in the bottom and, where centrifugal pumps 
are used for agitation, for preventing all but the very finest solids 
from passing through the pump. 

The following schemes of slime treatment are applicable to the 
slime end of a mill treating sands by leaching, but are designed 
particularly as complete methods for handling the entire mill out¬ 
put ground to what is practically a slime product by tube mills. 
These methods, on which patents have been applied for, are presented 
as an approach to the ideal and a practical realization of the ulti¬ 
mate simple, continuous,, automatic process toward which the best 
practice has been tending during the last few years. The principle 
of counter-currents is applied in an extremely simple manner, with 
the use of thoroughly efficient equipment, such as is now in use. 
The method first described was published by Mr. John E. Rothwell 
in Metallurgical and. Chemical Engineering for September, 1911. 

Reference to the graphic flow sheet which follows, will show 
that instead of the customary arrangement of the agitators in con- 
tinuous series, the agitators alternate with thickeners, each agitator 
receiving the thickened pulp from the thickener ahead of it and the 
decanted solution from the thickener following it. It will thus be 
observed that the solvent is taking up value from the ore of lowest 
value and passing it up to the tank containing a higher value, while 
the ore is losing value as it passes down through the successive tanks 
toward the discharge. 

This method is a wide departure from the practice used hereto¬ 
fore, and has many advantages, the more important of which are as 
follows: 

The dissolved values are recovered from the system at the point 
fartherest removed from the discharge of the tailings; thus it is 
impossible for a charge of pulp containing high value in solution to 
be thrown away bv an imperfect wash or carelessness or neglect on 


TILE CYANIDE PROCESS. 


15 


COLORADO 

IRON WORKS CO 


the part of the attendant operating a filter, as may happen with the 
older method. 

The solution carrying the pulp which passes to the filters is very 
low in value, promoting efficient washing. 

The amount of solution carried in the circuit is less than in 
other methods, while at the same time any unit of ore is in contact 
with a larger volume of solution than at present. 

By proper regulation, a minimum of solution of constant maxi¬ 
mum value is sent to the precipitation department, so that there is 
no occasion to carry two or more circuits for precipitation purposes. 

There will he no accumulation of solutions from which the values 
have to he precipitated and the solution thrown away. 

The power required for operating will be less and the equip¬ 
ment less for given tonnage capacity, thus the first cost for installa¬ 
tion will be less per day-ton treated. 

The two circuits maintained through the agitators and thick¬ 
eners may readily be followed by reference to the sketch. 

1 is the mill pulp thickener which receives all of the overflow 
from the slime classifiers, the clear overflow going back to the mill 
solution tank except the small amount sent to G for percipitation 
if there is a tendency on the part of this mill solution to build up 
in value. This solution, instead of being sent to G, might, in some 
cases, be sent to 4 or 3, whichever should happen to contain a nearly 
equal value per ton of solution. The underflow will be transferred in 
definite quantity and specific gravity by the automatic transfer T 
to the first agitator A. 

A, the first agitation tank, receives the thickened pulp from 1 
and the counter current solution from the overflow of 3. The con¬ 
tents of this agitator are delivered to thickener 2 by the adjustable 
sampling vane placed above the pulp level and which assures the 
continuous flow of a certain quantity without favoring coarse or 
fine, solid or liquid. 

2, the first dewatering thickener, receives the flow from the 
sampling vane of A, the clear overflow going to G and the thick 
underflow by automatic transfer to B. 

B, the second agitation tank, receives the thick pulp from 2 
and the counter current solution from the overflow of 4, and dis- 


10 


the cyanide process. 


COLORADO 

IRON WORKS CO 
















































































































































COLOR ADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


17 


charges its contents continuously at the same rate of flow as received, 
through the sampling vane to 3. 

3, the second dewatering thickener receives the flow from the 
sampling vane of B, the clear overflow goes to A, while the thickened 
underflow goes through the automatic transfer in definite quantity 
and specific gravity to C. 

C, the third agitation tank, receives the thick pulp from 3 and 
the counter current solution from the overflow of 5. It discharges its 
contents in equal quantity as received, through its sampling vane to 4. 

4, the third dewatering thickener, receives the continuous flow 
through the sampling vane from C. The clear overflow goes to B, 
while the thickened underflow goes through the automatic transfer 
in definite quantity and specific gravity to T). 

D, mixing tank, receiving the thickened pulp in definite quan¬ 
tity and specific gravity from 4, together with a continuous flow of 
barren solution from W equal (plus the proper quantity of water 
from X to make up for the moisture passing into the circuit from 1) 
to the counter current flow 7 . The contents of this agitator overflow 
continuouslv into 5. 

5, the fourth dewatering thickener, receives the pulp overflow 
continuouslv from I), the clear overflow going to C. The thickened 
underflow goes through the automatic transfer to waste, if sufficiently 
low in dissolved value and cyanide. If this pulp, however, contains 
too much value to waste, intermediate thickening tanks are placed 
between 4 and 5 and the overflow from 5 mixes with the thickened 
pulp going to the thickener immediately preceding it. If, however, 
it is desirable to filter and wash the thick slime, a revolving drum or 
pan continuous filter will follow 4, the thickened pulp being deliv¬ 
ered to the filter by the automatic transfer in the same manner as 
to 1) in the sketch. 

G. gold solution tank, receives the overflow from 2 and delivers 
to Z as required. 

Z, zinc boxes, receive solution from G and deliver barren solu¬ 
tion to S. 

S, barren solution tank, receives solution from Z from which it 
is raised by the pump P2. 

P, P2, pumps used to transfer solutions from 1 to mill solu¬ 
tion storage tank and from S to mill storage and to W. 

o cm 


18 


THE CYANIDE PROCESS. 


COLORADO 

IRON WORKS CO 


W, solution tank for barren solution used in counter current. 
Receives solution from S, through P2 and delivers to M. 

]\I, M2, measuring tanks or flow meters, receiving barren solu- 
tion from W and wash water from X, delivering in definite regis¬ 
tered quantity to D. 

X, water tank. 

The Rothwell-Lowden method, another and simpler means of 
application of the counter current method of continuous agitation, is 
illustrated in the following outline perspective drawing. In this, 
the thickening tanks are dispensed with and a quiet space provided 
within each agitation tank. This annular space is furnished with 
inclined baffles, similar to those employed in the Rothwell thickener, 
which greatly increase the settling area, and the solution drawn off 
is substantially clear and practically no solids are carried back by 
it. To remove any turbidity of the solution previous to precipita¬ 
tion it is passed through a clarifying filter previous to going to the 
gold tank. The method of operation is as follows: 

A, B, C, are Akins-Rothwell agitation tanks arranged for con- 

7 7 7 O O 

tinuous series agitation and each fitted with an inner cylinder A t , 
Bj, Cj, and an overflow launder L 1? L 2 , L 3 . In the annular area 
between the cylinder and the curb of the tank are placed inclined 


baffle plates, the tops of which are submerged. 

The slime pulp to be treated flows from the grinding mill to 
the space within the inner cylinder A 1? in which it is kept agitated 
by pneumatic or mechanical means, or both. A definite proportional 
part of the pulp is cut out continuously by the cutting vane and 
passed on to the space in the inner cylinder B 1? in which the same 
operation takes place, the pulp passing to tank C and so on to the 
subsequent tanks of the series. 

While this operation is going on, barren cyanide solution is 
passed from tank, W, through the meter, M, into the space in the 
inner cylinder of tank C, or the last tank of the series when more 
than three tanks are used, and this solution mixes thoroughly with 
the pulp being agitated, thus diluting the values carried in solution. 
Separation of the solids from the liquid is made by gravity in the 
quiet annular space 3, the solids remaining in the tank while the solu¬ 
tion overflows the weir into the launderer L 3 in quantity equal to 
the inflow from W. From the launder L g the solution flows to the 


COLOR ADO 

iron works co THE CYANIDE PROCESS. 10 



the counter current method of continuous agitation. 









































































20 


THE CYANIDE PROCESS. 


COLORADO 

IRON WORKS CO 


space in the inner cylinder Y> 1 of tank B, in which the action and 
operation are the same as in C, the overflow going from the space 
2 to the inner cylinder A, of tank A. 

The counter current solution, passed from W into C, diluting 
the values in solution in that tank, flows hack through the series of 
tanks, coming progressively in contact with richer pulp and gather¬ 
ing values in its course, finally overflowing from L x carrying a 
maximum value. This is the solution which is precipitated, for 
which purpose it is passed through the clarifying filter, F, to re¬ 
move any turbidity and thence to the gold tank, G, from which it 
flows to the zinc boxes, Z, in which the gold and silver are precipi¬ 
tated. The barren solution from the zinc boxes flows to the tank, S, 
from which it is pumped back to the tank, W, is built up in cyanide 
strength and re-enters the circuit. 

In the meantime the pulp has been passing through the series 
of tanks in a direction opposite to the flow of the solution, whereby 
it progressively comes in contact with solution lower in dissolved 
values and higher in free cyanide as the pulp becomes reduced in 
value, finally passing from C into the collecting tank, D, from 
which it goes to the slime filter. This filter separates the pulp and 
washes from it the soluble values it carries, delivering the solids 
to waste. The filtrate, being low in value, passes back to the grind¬ 
ing mill circuit, where it is built up in cyanide strength and re¬ 
sumes its flow through the system. 

This method of operation secures all the metallurgical advan¬ 
tages of the counter current principle as well as all of the operating 
advantages mentioned in the counter current method first described, 
together with further simplification and less equipment. 


III. Slime Filtration. 

The problem of separating the slime from the valuable solu¬ 
tion in which it is carried has been attacked from many directions 
and with such success that sliming is now deprived of its terrors 
and fine grinding with handling of the entire ore by slime treat¬ 
ment methods is the basis of most of the more recent and economical 
work. 

Among the numerous slime filters at present in use, the older 
are subject to various disadvantages, particularly in being inter- 


COLORADO 

IRON WORKS CO 


THE CYANIDE PROCESS. 


21 


mittent in action, expensive in installation and requiring consid¬ 
erable attention. Filters of the revolving drum type are continu¬ 
ous, automatic in operation, compact and low in cost and expense 
of maintenance. The most improved of the revolving drum filters 
provides for washing under a higher vacuum than is used for loading 
if desired, also for washing with both weak solution and water, 
with separate delivery of each, thus accomplishing all that is desir¬ 
able in respect of final washing of the slime and ability to properly 
dispose of the solution and water washes in the mill circuit. 



PARTIAE VIEW OF AN INSTALLATION OF SIX PORTLAND FILTERS. 


Slime can be separated from the valuable solution and washed 
by a system of repeated dilution and thickening but not without the 
addition of considerable volumes of water to the mill circuit. In 
washing on the filter, however, the final wash water can be regu¬ 
lated to an amount substantially equal to the moisture remaining in 
the cake at discharge so that there will be practically no addition 
to the amount of liquid carried in the circuit and no necessity of 

running large quantities of solution to v aste. 

The work of revolving drum filters containing these features is 
fully equal to any others, and where the soluble values in the pulp 









99 


THE CYANIDE PROCESS. 


COLOR ADO 

IRON WORKS CO 


have been low, as they ought to be at this point in a well-regulated 
plant, a mere displacement wash has given extremely low tails. 

IV. Precipitation of the Gold and Silver. 

Whether obtained from sands or slimes, the precipitation of the 
values from the solution is generally best made by zinc, either in the 
form of fine shavings or dust (zinc fume). It was very largely due 
to the efficiency of the MacArthur-Forrest zinc precipitation method 
that the cyanide process found such ready acceptance, previous 
attempts having been mostly in the direction of precipitating the 
values from the pulp without first separating it from the clear solu¬ 
tion. Could precipitation be effected from the mixture of ore and 
solution after the dissolution of the gold and silver the cyanide pro¬ 
cess would be very materially simplified and shortened, but experi¬ 
ence has shown the necessity of using clear solution, as the pres¬ 
ence of solid matter in suspension exerts a very detrimental effect. 

Precipitation by zinc shavings is very simple, and consists merely 
in passing the solution slowly through loosely packed zinc shavings 
contained in boxes of such design as to insure intimate contact of the 
solution and zinc. The results are best with fresh zinc, and it is 
customary to cut the shavings from sheet zinc at the mill, in a sim¬ 
ple automatic lathe designed especially for the purpose. 

There is considerable difference of opinion among operators 
with respect to the minimum strength and value of solutions which 
it is economical to precipitate, but under ordinary conditions it is 
best to have a small excess of free cyanide present. Opinions also vary 
as to the extent to which the values should be removed and in this, 
as in other steps in the process, it is possible to carry the precipita¬ 
tion to a point beyond which it proves economical. The remaining 
values of a few cents per ton of solution are not lost, nor is the 
excess cyanide, but the solution is run to a sump tank and used again 
after being brought up to strength. 

In precipitating very weak solutions, the gold and silver fre¬ 
quently deposit upon the zinc in a hard film, interfering with the 
efficiency of the zinc as a precipitant. This can be avoided by the 
use of a zinc-lead couple, formed by dipping fresh zinc shavings in a 
solution of lead acetate immediately before placing them in the zinc 
boxes, so as to coat them with metallic lead to the extent of about 


COLORADO 

IRON WORKS CO 


THE CYANIDE PEOCESS. 


23 


1 per cent, of the weight of the zinc, which causes the precipitate 
to form as a loose deposit. 

The other method of precipitation by zinc is with zinc fume, 
which consists of a powder of zinc containing more or less impuri¬ 
ties obtained as a by-product in zinc smelting. The impurity present 
in largest quantity is zinc oxide, which is usually removed by treat¬ 
ing the fume with dilute ammonia. In this process the zinc dust is 
mixed with the solution in proportion sufficient to precipitate the 
values and, after agitation in suitable apparatus, the whole is passed 
through a filter press, the solution going to the sump tank and the 
precipitate being obtained in the form of cakes. In a largely used 
patented process, the zinc dust is treated mechanically in a minia¬ 
ture tube mill, fed to the solution in definite quantity while in mo¬ 
tion and forced into a filter press without exposure to the air. 


V. Cleaning Up, Refining and Melting. 

The precipitate obtained by filter pressing as above described is 
ready for the process of refining. The clean up from the zinc boxes 
in precipitation by zinc shavings is carried out somewhat as follows: 
A strong; cyanide solution is run into the zinc boxes to loosen the 
precipitate, after which clean water is run in, sometimes with a little 
acid and alum to promote settlement. The shavings are shaken in 
the water to loosen adhering precipitate and after settling, the water 
is siphoned off and the precipitate removed in buckets or washed out 
if the zinc boxes are suitably arranged. I11 many of the larger plants 
the precipitate from the zinc boxes is filter pressed, which makes a 
great saving in time. The clean up occurs at intervals of one to four 
weeks, usually every two weeks. 

Following the collection of the precipitate in a moist condition 

o x 

the reduction to bullion may be accomplished in different ways, 
as: Drying and direct smelting; Drying, roasting and smelting; 
Acid treatment, drying and smelting; Smelting direct with litharge 
and cupelling; and feeding the dried precipitate into a bath oi lead 
in a reverberatory smelting furnace with subsequent cupellation of 
the lead. Each method has advantages and disadvantages and a 
consideration of all the conditions will indicate which will most likely 
prove best for any particular plant. These operations vary in de¬ 
tails as conducted in different plants, and for this reason a state- 


24 


tiie 


CYANIDE PROCESS 


COLOR ADO 

IRON WORKS CO 





.. a 




- s'wwsssewsssaj? 































































































































































COLOR ADO 

IRON WORKS CO 


THE CYANIDE PEOCESS. 


25 


nieiit of the exact procedure in one case would not represent the 
operations in another where conditions were different ; however, the 
illustration of a complete refining room shown on the opposite page 
will assist in an explanation of the final steps in the cyanide process 
resulting in the production of bullion. 

r flie gold precipitate and zinc shavings from the zinc boxes are 
screened through a 20-mesh screen and the product placed in the 
vacuum filter tank, which is the lowermost of the three tanks shown. 
The pump exhausts the air from beneath the filter bottom and dries 
the precipitate, which is then placed in pans and dried and calcined 
in the muffle furnace, after which it is charged into crucibles together 
with the necessary fluxes and melted in the crucible furnace, the 
doors of which will be seen just above the floor level. The ash pits 
immediately in front of the crucible furnace are provided with covers 
of steel plate, not shown, and an overhead traveler with hoist serves 
for handling the crucibles and pans. After fusion the melt is poured 
into conical moulds in which the bullion settles to the bottom and 
the slag collects at the top, the slag being detached after cooling. 

In continued operation a large amount of “shorts,” i. e., short 
zinc that will pass a two or three-mesh sieve but not a 20-mesh, 
accumulates after a time and as these cannot be utilized in the zinc 
boxes they are screened out and given the following treatment: They 
are first placed in the acid treatment tank, the uppermost one in the 
illustration, and a solution of one part sulphuric acid to about three 
parts water is added for the purpose of dissolving the zinc, which 
would otherwise cause the bullion to be of too low grade. The reac¬ 
tion is at first quite rapid, but toward the end agitation, or heating 
by steam also, if convenient, is required. This tank is lead lined and 
provided with a hood to conduct the noxious fumes developed to the 
outer air; the hood is provided with a length of pipe telescoping 
within the stationary portion and is counterweighted to facilitate 
access to the interior of the tank. 

After solution of the zinc, the charge is let into the washing and 
decanting tank shown just above the pump, hot water added, and the 
precipitate washed by decantation two or three times to eliminate 
the zinc sulphate formed in the acid treatment. The residue, now 
freed from the great excess of zinc, is washed into the filter tank 
and the treatment continued in the manner first described. 


PRELIMINARY TESTS. 


COLOR ADO 

IRON WORKS CO 


26 


Preliminary Tests. 

A few tests will serve to determine whether or not an ore is 
amenable to treatment by the cyanide process, and in most cases the 
line of further experimentation will be indicated, at least in a gen¬ 
eral way. For the working out of a system of treatment which will 
give the best possible results in regular operation a much more ex¬ 
tensive series of tests is demanded. These latter tests should be on 
larger quantities of ore than the preliminary ones and the conditions 
obtaining in actual practice should be simulated as closely as possible. 

The methods of conducting tests of this nature cannot be entered 
into with sufficient detail here. They will be found in the more 
important treatises on the cyanide process, and in any event should 
be entrusted only to those having knowledge and experience in this 
special field. The physical properties of an ore and the composition 
as indicated bv chemical analvsis can at best but indicate the direc- 

t/ VI 

tion of the investigation; the final tests are experimental in their 
nature and, if intelligently prosecuted and methodically recorded, 
lead by a process of elimination to that system which, all things 
considered, will prove the best one to adopt. 

That the best method of treatment for anv ore can be determined 

* 

in this way is no longer disputed. While variations will be found 
between the results obtained and those secured in actual working: 
on a large scale, they are too small to affect the general result, and, 
as they concern different steps in the process, these experimental 
errors tend to balance each other. In short, it may confidentlv be 
asserted that cyanide tests are at least as reliable as tests of the 
metallurgical treatment of ores by any other wet method. 

If the general lines of treatment are well chosen and additional 
tests upon the current product have proved them advisable, slight 
changes in the treatment can be made and the highest economical 
recovery attained and maintained. Not so if the method and equip¬ 
ment are not those best suited to the ore. 

Those desiring to have ores tested are invited to communicate 
with us for information as to quantity of ore required, cost of the 
investigation and other particulars. 


COLOR ADO 

IRON WORKS CO 


MILL PLANS. 


27 


Mill Plans. 

In the present edition of our cyanide catalogue we have decided 
to show drawings of but two mills and these of the simplest kind. 
The reason for this is that in large plants it is usually economical 
to add a number of refinements not essential in small installations, 
and as these details differ according to circumstances, it would be 
impossible to present plans of large plants which would be of gen¬ 
eral application. 

A description of a metallurgical process such as it is our cus¬ 
tom to publish as an introduction to our catalogues, can at best but 
give an outline of the state of the art at the time it Avas written and 
where rapid advancement is being made, as is the case Avitli the 
cyanide process, such description must soon become obsolete. This 
is forcibly illustrated by the last edition of this catalogue, the intro¬ 
duction to Avhicli the short four years since it appeared have seiwed 
to render totally unsuitable to reprint as a description of the cyanide 
process as it stands today. The most noteAvorthy change in prac¬ 
tice has come from the solution of the slime problem, resulting in 
the possibility of the sufficiently fine grinding of the whole ore to 
handle it by slime treatment methods. This has led to simplifica¬ 
tion of equipment, uniformity and ease of control and to a decrease 
in the cost of operation. 

Mill plans are even more apt to become unsuitable than descrip- 
ti\ r e matter, especially plans of the larger mills, and as the present 
aim is to acquaint those without knowledge of the process with the 
general methods and the reasons therefor, any specialization is super¬ 
fluous and can be submitted Avhere the occasion for it arises. 

We treat each problem according to the special conditions and 
it has been our experience that, except Avitli the simplest plants, 
there are no two propositions Avhich can be met in the same Avay. 

A large and varied experience in the design and building of 
cyanide plants keeps our engineering department at all times sup¬ 
plied with drawings made for special cases, Avhich, Avhile not appli¬ 
cable to other conditions, are of great value in the preliminary dis¬ 
cussion of plants requiring treatment along similar lines. These AA r e 
are always ready to submit on occasion and Ave solicit inquiries from 
those projecting cyanide plants accompanied by all available data 
as to conditions and requirements. 


28 


DRY CRUSHING CYANIDE PLANT. 


COLORADO 

IRON WORKS CO 




A SMALL DRY CRUSHING PLANT. 

























































































































































































































































































COLORADO 

I ROM WORKS CO 


DRY CRUSHING CYANIDE PLANT. 


20 


A Dry Crushing Cyanide Plant. 


^ e luive illustrated herewith a general arrangement of one of 
the simplest of the dry crushing process plants. In this plant the ore 
is received from the mine in cars and delivered to the mill first over 
the grizzley above the ore bin, the product of the grizzley passing direct 
to the ore bin, and the oversize from the grizzley going through the 
crusher and from the crusher into the same bin. From the ore bin it 
is led by a plunger feeder to a set of rolls adjusted for coarse crush¬ 
ing, the product of the rolls going to the elevator and being elevated 
to a revolving screen, usually of d/16 or ^-inch aperature, wire cloth 
or perforated metal. The oversize from the revolving screen is re¬ 
turned to the coarse crushing rolls, while the portion which has 
passed through this screen goes to an impact screen having screen 
cloth of suitable mesh, this depending on the size to which it is 
necessary to crush the ore. The product passing this impact screen 
passes direct to the storage bin, the oversize going to a second set of 
rolls set for fine crushing, the product of which is returned to the 
same elevator. The finished product in the storage bin is loaded into 
a car that runs on a track over the leaching tanks and the tanks are 
loaded with a given quantity of this sand product until they are 
within about three or four inches of the top. Cyanide solution of 
some definite strength is usually admitted at the bottom of the tank 


through a filter and allowed to rise to the surface as the sand is 
charged to the tank, then the operation is reversed and cyanide solu¬ 
tion admitted to the top of the tank and leached through and into 
the gold tanks; this operation being continued as long as values are 
economically extracted from the sand. The gold tanks provide a 
storage for the valuable solution, and from them it is drawn through 
the zinc boxes in which the gold is recovered, the barren solution 
then going to a sump tank, from which it is pumped to the solution 
storage tanks, there regenerated with cyanide and used again in the 
sand leaching tanks. The zinc boxes are cleaned up at intervals and 
the gold contained therein separated from the coarser zinc and sent to 
the refining plant, where it is fluxed and melted into bars. 


30 


WASHING BY CONTINUOUS DILUTION. 


COLOR ADO 
IRON WORKS CO 



I 


20 Forts Or C#c 


20 Fo#j W#re/r Ps# 20 


/ 21. 7o#* Wsrf/r 


_t_ 

30 

-r 



WASHING BY CONTINUOUS DILUTION. 
































































COLORADO 

IRON WORKS CO 


WASHING BY CONTINUOUS DILUTION. 


Q 

O 


1 


Washing by Continuous Dilution. 

The annexed flow sheet illustrates a continuous method of amal¬ 
gamation and cyanidation, using the patented system of continuous 
agitation in connection with washing by progressive dilution. 

For the purpose of illustration, certain arbitrary assumptions 
have been necessary. These are: An ore carrying $20.00 per ton 
in gold and a daily capacity of twenty tons; the total recovery being 
taken at about 95 per cent., $7.00 by amalgamation, $12.00 by 
cyanide, with a loss in the tailings of $1.00 insoluble, and $0.0366 
soluble value. The flow sheet has been made self-explanatory as far 
as possible, and will be readily understood with the help of the follow¬ 
ing key: 

1, A 7 x 10 Blake Crusher. 

2, The Ore Bin. 

3, The Battery Feeder. 

4, A Five-Stamp Mill. 

5, The Mill Solution Tank. 

6, Amalgamation Plates. 

7, Akins Sand and Slime Classifier. 

8, A five-foot Continuous Grinding Pan. 

9, The Mill Thickener. 

10, Adjustable Stroke Diaphragm Pump. 

11, 12, 13, Three 1055 Cu. Ft. Akins-Kothwell Agitation Tanks 

14, A 30-inch Mixing Cone. 

15, The First Dewatering Thickener. 

16, Adjustable Stroke Diaphragm Pump. 

17, A 30-inch Mixing Cone. 

18, The Second Dewatering Thickener. 

19, Adjustable Stroke. Diaphragm Pump. 

20, A 30-inch Mixing Cone. 

21, The Third Dewatering Thickener. 

22, Adjustable Stroke Diaphragm Pump. 

23, A 30-inch Mixing Cone. 

24, The Fourth Dewatering Thickener. 

25, Adjustable Stroke Diaphragm Pump. 

26, Gold Solution Tanks. 

27, Zinc Boxes. 

28, Sump Tank for Barren Solution. 

29, Mill Solution Tank. 

30, Water Tank. 


9 0 


AMALGAMATION AND CYANIDE PLANT. 


COLOR ADO 

IRON WORKS CO 






















































































































































































































































































































COLORADO 

IRON WORKS CO 


AMALGAMATION AND CYANIDE PLANT. 


Q Q 
0(1 



ELEVATION OF AN AMALGAMATION. CONCENTRATION AND CYANIDE PLANT 




























































































































































































































34 AMALGAMATION AND CYANIDE PLANT. , R0N works co 

Amalgamation, Concentration and Cyanide Plant. 

The accompanying drawings show the general arrangement of a 
plant for the treatment of gold and silver ores, using amalgamation 
and concentration with fine grinding of the tailings, their cyanida- 
tion by agitation, and slime filtration for final recovery of the valu¬ 
able solution. The plant illustrated will have a capacity of about 
fifty tons per day but any desired capacity can be provided for along 
similar lines. The power plant is not shown, as it is not material 
to the purpose in hand, and will be governed by local conditions-. 

The flow of the ore through this plant is explained below, using 
Dr. Richards’ excellent method of description: 

1, Ore Grizzley; oversize goes to 2, undersize to 3. 

2, Blake Crusher set to reduce the ore to about ; product 

goes to 3. 

3, Mill ore storage bin. 

4, Bin Gates. 

5, Stamp Battery Feeders; receive crushed ore from 3 through 
4, and deliver it automatically as required to 6. 

0, Stamp Battery, in which the ore is reduced to pass a screen 
the size apertures of which is determined by the fineness of 
the ore necessary for the after treatment. The ore is crushed 
here in about five tons of solution to one ton of solids and 
passes through the screen to 7. 

7, Silver Plated Copper Amalgamating Plates on which the coarse 
metallic gold and silver are caught in an amalgam, the tailings 

w O/ O 

and solution passing to 8. 

8, Three Compartment Spitzkasten; the underflow of the first 
and second compartments going to 0, underflow of the third 
or largest compartment, going to 10, and the overflow of the 
third compartment going to 14. 

9,. Concentrating Tables; receive the underflow of first two com¬ 
partments of 8, concentrates going to storage bins, tailings 
with practically all of the solution going to 11. 

10, Slime Concentrating Table; receives the underflow of the third 
compartment of 8, concentrates going to storage bin, tailings 
with practically all of the solution going to 11. 


COLOR ADO t T „ 

iron works co AMALGAMATION AND CYANIDE PLANT. 35 

11, Sand Pump or Elevator 5 receives tailings and solution from 9, 
10 and 13 and delivers to 12. 

12, Akins Classifier* receives tlie flow from 11 and separates the 
sand from the slime, the sand going to 13 and the slime with 
most of the solution going to 11. 

O o 

13, Tube Mill; receives the sand product of 12, together with suf¬ 
ficient solution to make the proper consistency for grinding. 
The ground product goes to 11. 

14, Rothwell Continuous Pulp Thickening Tank; receives the over¬ 
flow from 8 and 12. The clear overflow goes to 15 and the 
thick underflow goes by 16 to 17. 

15, Triplex Solution Pump; receives the overflow from 14 and 
delivers it to 28. 

16, Diaphragm Pump; removes the thick pulp from 14 continu¬ 
ously and delivers it to 17. 

17, Three Akins-Rothwel 1 Agitation Tanks; for the patented con¬ 
tinuous series operation, receive the thick pulp in cyanide solu¬ 
tion from 16 and carry it by continuous flow through the cut- 
ting vane on each tank, delivering it from the last tank of the 
series to 19. 

IS, Centrifugal Pumps attached to the tanks for agitation purposes. 

19, Distributor for slime filter, receives the thick pulp continuously 
from the last agitation tank, 17, and delivers it at a constant 
rate to 20. 

20, Portland Continuous Slime Filter; receives the thick pulp from 
19, separates and washes the solids, the filtrate going through 
23 to 24, the solids to waste. 

21, Wash Water and Wash Solution Feed Pipes; receive wash 
solution from 29 and wash water from water storage, spray 
them on the slime cake on the filter medium through Avhich 
they are drawn by 23. 

22, Excess Wash Solution Box, to prevent wash solution from 
entering pulp loading tank. 

23, Wet Vacuum Pump, draws filtrate from 20 and delivers it 
to 24. 

24, Gold Solution Tanks; receive clear solution filtrate from 20 
through 23 and deliver it to 25. 

25, Zinc Shaving Precipitation Boxes, receive gold and silver- 


36 


AMALGAMATION AND CYANIDE PLANT. 


COLORADO 

IRON WORKS CO 


bearing solution from 24, retain the gold and silver and pass 
the barren solution to 26. 

26, Barren Solution Storage Tanks; deliver to 27. 

27, Barren Solution Pump; draws solution from 26 and delivers 
it to 29. 

28, Mill Solution Tank, receives from 14 through 15 and delivers 
into mill circuit. 

29, Barren Solution Storage Tank; receives from 26 through 27 
and delivers to mill circuit as required. 

30-31. Compressor and Air Receiver; furnish compressed air for 
aeration in the agitators and for the blow at point of discharge 
of the Portland filter. 

The precipitate of gold and silver held in the zinc boxes is 
cleaned up at intervals and either refined on the ground and shipped 
as bullion or partially dried and shipped in sealed cans to some 
custom refinery or smelter. 


COLOR ADO 

IRON WORKS CO 


AGITATION OF SAND AND SLIME. 


37 


Treatment of Sand and Slime by Agitation. 


Some ores do not require reduction to an all slime product to 
obtain the maximum profitable extraction, but yield to cyanide by 
30 to 40 hours agitation when crushed to 24 or 30 mesh. Formerly, 
the treatment of such a product would have involved the separa¬ 
tion of the sands and slimes preliminary to cyanidation, with leach¬ 
ing of the sands in sand tanks and the dewatering and treatment 
of the slimes by agitation and filtration. 

A method which we have devised, eliminates the sand tanks and 
provides for handling the entire product together in a practically 
continuous manner. The operation is as follows: 

The product of the stamps, Chilean mills or the unclassified 
tailings from the concentrators are sent to an Akins classifier in 
which the sands are separated from the slimes, the former going 
direct to the first of a series of agitation tanks arranged for the 
patented system of continuous agitation, the latter, with the excess 
of solution passing to a Rothwell continuous thickener. The thick¬ 
ened pulp from the thickener is raised by a diaphragm pump into 
the first agitation tank and the clear overflow is returned to the mill 
circuit. 


During agitation the pulp passes continuously from tank to 
tank and is discharged from the last tank of the series into an Akins 
classifier which separates the sand from the slime, the sand going 
to a two-stage Akins classifier where it is given a double wash and 
is discharged as waste. The water used for the final wash is passed 
to the classifier in which the first wash is given and from there to 


the final thickener, the slime overflow from the classifier immedi¬ 
ately following the agitation tanks also going to this thickener. The 
clear overflow from this thickener goes to the gold tank and the 
thickened pulp to a Portland continuous filter where it is separated 
from the solution, washed and discharged to waste, the filtrate going 
to the gold tank. The solution from the gold tank goes to zinc boxes 
for precipitation of the values and the barren solution is returned to 

the mill circuit. 

Where dry crushing is practised the dry pulp would be mixed 
with a definite quantity of solution and passed direct to the first 
ao-itation tank, the preliminary classification and thickening being 
dispensed with. 


38 


CONCENTRATION AND CYANIDE PLANT. 


COLORADO 

IRON WORKS CO 


Double Concentration with Cyanidation. 

With some ores it is necessary to crush and concentrate in water 
and then to dewater the tailings and continue the treatment by 

O e/ 

cyanide. 

In a plant recently designed and equipped by us it was neces¬ 
sary to follow this line of treatment of an ore in which the mineral 
was very finely disseminated in a siliceous gangue and required 
double concentration, the second concentration after tube milling. 

The final tailings from concentration are dewatered by first 
going to a Rothwell continuous thickener which delivers clear water 
at the overflow and a pulp containing about 60 per cent, moisture 
at the bottom of the cone. The thickened pulp goes to a Portland 
continuous slime filter with a tank giving about 60 per cent, sub¬ 
mergence to the drum, and the loaded cake, dried to about 30 per 
cent, moisture is sprayed with a solution of lime, thus effecting 
neutralization of a minimum amount of the mill water, and then 
with cyanide solution just prior to discharge, to displace most of 
the water and prevent the accumulation of solution in the cyanide 
department. 

The pulp from the dewatering filter is delivered to a mixer in 
which it is thoroughly incorporated with cyanide solution in the 
ratio required for agitation, passing thence into the first agitation 
tank. The agitation tanks are arranged for operation by the Roth- 
well-Lowden method of counter current continuous agitation de- 

o 

scribed on page IS. 

The pulp from the last agitation tank passes continuously to 
the Portland continuous revolving filter where it is separated from 
the solution, washed and discharged to waste, the pregnant solution 
for precipitation passing continuously from the first agitation tank 
through the zinc boxes and thence going in part to form the dis¬ 
placement solution on the dewatering filter but the bulk going back 
as the counter current through the agitators. 

O o 

In this method the solution precipitated amounts to but two 
and one-half to three tons per ton of ore treated. 


COLORADO 

IRON WORKS CO 


TAILINGS CYANIDE PLANT. 


39 


A Plant for Treating Accumulated Tailings. 

A plant recently designed by ns for treating a tailings pile hav¬ 
ing not over 15 per cent, minus 200 mesh, is briefly described as 
follows: 

From the tailings pile the pulp is conveyed to a trommel cov¬ 
ered with a %-inch mesh screen which removes chips, rock and 
other coarse debris that have accumulated in the deposit, the under¬ 
size passing to a storage bin. From the storage bin it is fed by a 
belt-driven plunger feeder to a mixer with addition of sufficient 
cyanide solution to make a thick pulp. In this the coarser lumps are 
broken up, the product flowing to a double log washer type of mixer 
in which three parts dilute cyanide solution is added for each part 
solids, the pulp then flowing to a slime pump which raises it to an 
Akins sand and slime classifier. This classifier separates the sand 
from the slime, the sand product going into a bath of water in a 
second Akins classifier where it is washed to save any values taken 
up by the solution which it carries as moisture and is discarded as 
waste. 

The slime overflow from both classifiers goes to a Rothwell 
thickening tank, in which it is thickened to a pulp containing about 
one and three-fourths parts liquids to one part solids, the clear over¬ 
flow going to a pump by which it is raised to the mill storage tank 
for reuse. The thickened pulp passes to the first of a series of 
four a ° it at ion tanks, connected for the patented system of continuous 
agitation, go in2: successively through the four tanks and into a col- 
lecting tank of small capacity from which it is distributed to Port¬ 
land continuous revolving drum filters which separate the solids 
and wash them to recover values carried as moisture, after which 
thev are discharged to waste. 

The filtrate from the Portland filters goes to a collecting tank, 
thence to a clarifying press and finally through zinc boxes for pie- 
cipitation of the gold and silver. The barren solution from the zinc 
boxes goes back into the mill circuit, being brought up in strength 
for reuse, and the precipitate is melted into bullion. 


40 


TUBE MILLS. 


COLORADO 

IRON WORKS CO 



4 5-INCH BY 15-FOOT TUBE MILL. 




V/VLUA/IL'U __ _ _ A -4 

iron works co 1 UBE MILLS. 4:1 

Tube Mills. 

The past few years have served to strengthen the position of 
the tube mill as the best machine for the fine grinding of ores for 
cyanide treatment and they are to be recommended for this work 
in preference to all others except where small capacity and diffi¬ 
culty of transportation favor the use of grinding pans. 

In the design and construction of our tube mills we have aimed 
to make them most substantial in every way, so that purchasers may 
be assured that none better can be obtained in all those details which 
make for efficiency and complete satisfaction in use. 

The heads are of cast iron heavily ribbed and the shells of 
heavy mill steel plates with outside butt straps so placed as to pre¬ 
serve the balance and insure smooth running. All rivets have conn- 
tersunk heads on the inside, leaving the interior of the mill smooth. 
The scoop feed has proved a perfect means for supplying pulp to the 
mill and this part is made reversible, so that the mill may revolve 
in either direction. The discharge is through a large opening 
through the trunnion, provided with either a removable screen or a 
reverse spiral to prevent the egress of pebbles. The scoop feed is 
sufficiently large to admit the charging of pebbles through it while 
the mill is in operation. 

Both main bearings are of the ball and socket type and very 
massive, and special consideration has been given to the manner of 
attachment of the gear, to enable its easv renewal when necessary. 
We provide two manholes, on opposite sides of the periphery, one 
near each end, that access may be had to all parts of the interior 
without removing the pebbles. The usual method of driving is by 
spur gears and friction clutch or tight and loose pulleys, but we 
also furnish a bevel gear-drive when desired. Prices are quoted 
for the mill complete without lining, which is extra. We recom¬ 
mend and usually supply El Oro lining, but if preferred, will fur¬ 
nish silex blocks, manganese or ordinary steel. We build tube mills 
in all sizes ordinarily used. 

Tube mills are also built to run on tires, and claims are made 
by those who advocate this method, which are apt to be misleading. 
A cylinder mounted in this way may, and probably will, run easily 
when new, but the wear on the tires and rollers is extreme and the 
power required to drive the mill will, after a short period of use, 
greatly exceed that of one mounted on trunnions. The renewal of 
tires and rollers is a difficult operation, involving much labor and 
expense, and there are many bearings to look after, all in a bad 
location. The trunnion mill has but two bearings and, if these are 
proportioned to the load, they give no trouble and will maintain 
the gears in mesh and resist the driving thrust in the best manner 
possible. 


42 


TUBE MILLS. 


COLOR ADO 

IRON WORKS CO 


El Oro Tube Mill Lining. 

The most serious problems confronting tube mill operators con¬ 
cern the lining. A lining of silex blocks embedded in Portland 
cement gives a tube mill more capacity than a lining of plain bard 
iron or steel plates, as on the latter tlie charge of pebbles has a ten¬ 
dency to slide down in a mass instead of rolling over each other as 
they should. A silex lining, however, if not placed with special 
skill, is apt to cause trouble by portions falling out, and the time 
required to reline a mill with silex blocks, including the time neces¬ 
sary for the setting of the cement, usually puts the mill out of com¬ 
mission for five days. 



El Oro tube mill lining was developed at the plants of El Oro 
Mining & Railway Company, and the Compania Minera Las Dos 
Estrellas, at El Oro, Mexico, and consists of plates, usually of hard 
iron, having ribs of such form as will cause pebbles of suitable size to 
become firmly wedged between them, thus throwing the wear upon 
the pebbles and prolonging the life of the lining to two or three 
times that of steel or silex. 

In operation, when a pebble becomes fractured or worn and 
escapes from the place in which it was held, another will take its 
place and the effect is to maintain what is practically a flint lining 
to the mill. The rough surface presented entirely avoids the tendencv 

tJ 


COLORADO 

IRON WORKS CO 


TUBE MILLS. 


43 


of the whole charge to skid on the lining with the consequent great 
wear of the latter and small crushinp 1 efficiency. 

o J 

I he illustration showing the sections of this lining will make the 
construction clear without much explanation. One of the plain sec¬ 
tions is shown and also a liner for the manhole cover, as well as one 
of the sections abutting the manhole. They are attached to the shell 
of the tube mill by bolts, the entire relining can be done by ordi¬ 
nary unskilled labor, and the mill need not be out of operation over 
twenty-four hours. Experiments at El Oro, where seventeen tube 
mills are in operation, demonstrated the superiority of this lining 
on all points of comparison, and it has fully met all that was ex¬ 
pected of it since its installation in other mills. 

The manner in which the pebbles lodge in the grooves is a matter 
of surprise to those who have never seen it, as may be judged from 



INTERIOR VIEW OF TUBE MILL WITH EL ORO LINING. 

the illustration on this page, which is reproduced from a photograph 
of the interior of a tube mill which had been in operation for two 
months. El Oro tube mill lining may be successfully used in any 
tube mill with flint pebbles for either wet or dry grinding. 

We manufacture El Oro lining under special license from the 
owners of the patents, who have wisely established a royalty charge 
so low as to leave a large margin of saving for tube mill users. This 
charge is in the form of a payment per pound weight of lining, which 
we include in our price, there being no further charge to the user 
by reason of the patent. 






44 


GRINDING PANS 


COLORADO 

IRON WORKS CO 



CONTINUOUS GRINDING PAN 
































COLOR ADO 

IRON WORKS CO 


GRINDING PANS. 


45 


Grinding Pans. 

The recent tendency toward the exclusive use of tube mills 
for tine grinding has caused many to lose sight of the good qualities 
of properly constructed pans. It is true that most competitive tests 
have shown results in favor of the tube mills, but the results have 
not been so conclusive as to indicate the passing of grinding pans, 
and those having difficult transportation problems to contend with, 
as well as those operating small plants, are fortunate in having in 
grinding pans the means of closely approaching if not equalling the 
economy of regrinding with tube mills. 

The illustration on the opposite page shows our latest improved 
continuous feed and overflow grinding pan, a number of which we 
have supplied to cyanide plants, and which we believe to be superior 
to any elsewhere obtainable. It is five feet in diameter, with shoes 
and dies of form similar to those of the Wheeler amalgamating pan, 
but in all its features designed and constructed with special refer¬ 
ence to the requirements of regrinding in cyanide work. 

The pulp for regrinding is led into an annular feed box sur¬ 
rounding and attached to the upper part of the driver and passes 
downward through four pipes to the inner edges of the mullers. In 
the upper edge of the curb an annular space will be seen, which is 
intended to receive a continuous strip in order to secure the desired 
height of curb. Wood or lead is used for this, as the overflow can 
then be made level independently of the bottom of the pan. 

The discharge is over the edge of the curb into the launder sur- 
rounding the pan and the height of the curb together with the amount 
of water supplied regulates the fineness of product, more water be¬ 
ing used for a given size with a high curb than with a low one. \ liree 
equidistant plows held in sockets attached to the inner surface of the 
curb serve to agitate the pulp and direct it toward the center. The 
dovetail sockets on the outer edge of the feed box are for compen¬ 
sating weights not shown in place in the illustration. 

The weight of these pans without the timber framing is 7,500 

pounds each. 


46 


CLASSIFIERS. 


COLORADO 

IRON WORKS CO 


The Akins Classifier. 

(Patented) 

The separation of sand from slime is an essential step in almost 
all methods of cyanidation but one which cannot he said to have 
been satisfactorily accomplished until the advent of mechanical classi¬ 
fiers and even then, until the Akins classifier was placed upon the 
market, the means available were far from all that could be desired 
in simplicity and freedom from attention by those operating them. 

The Akins classifier consists of a trough enclosing a revolving 
helix. The trough, which is set with an inclination downward toward 
the slime discharge, has at one end an overflow weir and hopper for 
the slime and water product, and at the other end a discharge hopper 
for the sand product. Revolving within the trough is a shaft carry- 

-L O C t/ 



45 IN. BY 13 FT. AKINS CLASSIFIER. 


ing a single, continuous helix or spiral at the overflow end for part 
of the length and a double interrupted helix or spiral for the balance 
of the length of the trough. The feed inlet is so placed that the 
pulp is led into the trough below the surface of the charge. The 
spiral is gear-driven and revolves at from three to five revolutions 
per minute. 

In operation the thin pulp entering the feed box meets the 
slowly moving spiral, the heavier solids settle to the bottom of the 
trough and are gently advanced out of the surface of the charge 
toward the sand discharge end, the intermittent spiral permitting the 
contained moisture to flow back into the charge, the slow turning over 
of this sand washing the finest solids back and allowing the sand to dry 



COLORADO 

IRON WORKS CO 


CLASSIFIERS. 


47 


or give up all moisture except that held by capillary attraction. The 
lighter solids suspended in the liquid flow over the weir into the 
collecting hopper, to the slime launder. 

The machine is practically self-contained, and the only parts 
which require attention are the shaft journals which require oiling 
at long intervals. The spirals will last for years, as they move 
slowly and are only in contact with the sand a small part of the 
revolution. 

The absence of cams, cranks, lifting devices, connecting rods 
with their connecting pins, shafts and hearings, all requiring lubri¬ 
cation, attention and renewals, has secured its ready acceptance by 
cyanide operators and its superior efficiency and flexibility of ad¬ 
justment has been the cause of much enthusiasm on the part of users. 

In practice it has never been found necessary to lift or dig out 
the spiral, even after the machine has been stopped, the pulp con¬ 
tinuing to flow into the trough for a considerable time. When power 
is applied again, the spiral starts readily, without excessive strains, 
and in a few revolutions is working in a normal condition. 

In addition to the separation of sand from slime the classi¬ 
fier is used in special cases for dewatering concentrates, and also 
in a continuous washing system for sands, in which three or more 
machines are placed in series, one above the other, the lower one in 
each case receiving the sand discharge from the one directly above, 
with the wash water or diluent, the overflow from the lowest being 
used as diluent for the one above. Thus while the dissolved value 
contained in the sand is being reduced, the overflow solutions are 
built up in value. 

This arrangement offers a practical continuous system of wash¬ 
ing sand and the elimination of the large intermittently operated 
tanks now used. The method is not an experiment in any way, as 
it can be seen in successful operation in one of the largest milling 
plants in Colorado. 

The success of the Akins classifier has been little short of 
phenomenal, considering the special nature of its work and the brief 
time which has elapsed since its introduction and we have rarely 
heard of a machine which has had such pronounced success from 
the start. We recommend it without reserve. 

It is made in five sizes, 24 in. x 8% ft., 40 in. x 10 ft., 36 
in. x 12 ft., 45 in. x 13 ft. and 60 in. x IS ft., the dimensions being 
the diameter of the helix and the length from the overflow weir to 
the edge of the sand discharge. 


48 


DISTRIBUTORS. 


COLORADO 

IRON WORKS CO 


Distributors for Sand Tanks. 

We have built a great many distributors for the automatic filling 
of sand tanks and have recently brought out the one shown below. 
This is by far the simplest ever devised, and by reason of its low 
cost there will rarely be anv advantage in making one distributor, 
running on rails, serve for a number of tanks, as has heretofore been 
usual, except in the larger sizes. 

The distributor revolves on a spindle extending downward into 
the top of the column and a sleeve which forms part of the bowl sur¬ 
rounds the bearing, verv effectuallv excluding dirt. The deflecting 
plates on the ends of the pipes permit a nice adjustment for securing 
even distribution. The column which serves for the support of the 
distributor is made of a length suitable to the depth of the tank and 



is permanently fastened to the center of the bottom. The moving 
part can be lifted out without the use of tools, and there is nothing 
in the construction to get out of order. This distributor incidentallv 
solves the problem of head room, which so often presents itself in the 
installation of distributors running on a trolley. It is made and 
recommended for tanks up to 28 feet diameter. Tor tanks e30 feet 
and over in diameter we build distributors of another style. 

As previously stated, the distributors shown are those of most 
general application; but upon receipt of information as to the con¬ 
ditions to be met we will recommend such as will best serve. Auto¬ 
matic distributors are greatly to be preferred to filling tanks by hand, 
even where labor is cheap, as the man directing the hose, although in¬ 
telligent and careful, cannot produce such regular work. 






COLOR ADO 

IRON WORKS CO 


FILTER BOTTOMS. 


49 


Filter Bottoms. 



W e make various styles of filter bottoms, several different forms 
°f construction being shown in the accompanying cut, styles “B” and 
,' however, being the most favored. In style “B” the lower slats 
are spaced to suit the load on the grating strips above, and are notched 
on the bottom to permit the solution to flow to the outlet of the tank. 
The grating is made of one inch square pine, with spaces of one inch 
between the strips and a strip is placed around the outer edge of the 
grating, over which the filter cloth is laid and caulked with a rope in 
the annular space. 

Style “C” is similar to “B,” except that instead of the grating 
of one inch square pieces, this is formed of perforated boards cut to 
suit, the perforations being one inch in diameter and equally spaced 
at frequent intervals. 


Style “13” is arranged to slope downwardly towards the center of 
the tank at from 3 degrees to 5 degrees from the horizontal. The 
supporting strips are cut in segments and spaced close enough to suit 
the load on the perforated floor above. This floor is similar to that 
used in style “C,” except that it is in pieces that run radially. The 
supporting strips are notched on the under side to permit of the free 
flow of solution to outlet of tank. 

Style “E” is the kind of filter frame used when the pneumatic 
system is put in the leaching tanks, and the air for agitation and 
oxidation passes through the filter and up through the mass of ore. 
This arrangement takes the place of the air headers and pipes some¬ 
times used. The filter is made to slope towards the center of the 
tank in a manner similar to style “D”. 



















































50 


DISCHARGE GATES. 


COLORADO 

IRON WORKS CO 


Discharge Gates and Doors. 



The square side discharge door here shown is of cast iron and 
is made to suit the cur¬ 
vature of the tank. The 
door seats against a rub¬ 
ber cushion and is fas¬ 
tened by means of a 
hand wheel as shown. 

We furnish this dis¬ 
charge door in the fol¬ 
lowing sizes: 

7x 7 in., weight 75 lbs. 

10x10 in., weight 125 “ 

12x12 in., weight 165 


The style of bottom discharge gate, as shown in the lower illus- 

o o 

tration on this page, is made of cast iron, with a discharge opening of 



12 inches, the steps in the 
casting being made to ac- 

O o 

commodate the filter frame 
and rope caulking space of 
the filter. A rubber gasket 
is inserted against which 
the swinging valve door 
seats, making a perfectly 
tight joint. The arrange¬ 
ment of this gate with the 
key permits of a quick 
and full opening, through 
which the charge is flushed 
into the tailings sluice un- 
derneath. The weight of 
this gate is 165 pounds, 
and it is one of the most 
practical styles of bottom 
discharge gates made. 











COLORADO 

IRON WORKS CO 


DISCHARGE GATES. 


51 



QUICK OPENING GATE VALVE. 



The other illustration on this page shows 
our bottom discharge gate operated from the top 
of the tank. The valve is of cast iron and seats 
on a rubber gasket. 

o 


The above illustration shows one of a line of quick opening, all 
iron gate valves which we make especially for use in cyanide plants. 

A comparison of the weights and dimensions 
given below with those of standard valves will 
show them to be of only about one-fourth the 
thickness and one-third the weight of the latter. 
The bodies of these valves are made of the same 
diameters as pipe flanges of corresponding sizes 
and they are attached by bolts passing entirely 
through the valve and adjacent flanges, except 
on the side toward the hood, where the holes 
are threaded for cap screws. 

They are of ample strength and weight, and 
are thoroughly well fitted. They are especially 
recommended as an efficient and serviceable 
valve for slime tanks, where their small thick¬ 
ness will be welcomed on account of the material 
saving in head room. 


SIZE 


THICKNESS 


WEIGHT 


4 inch 

5 inch 

6 inch 

7 inch 

8 inch 
10 inch 


3 inch 
3 inch 
3!4 inch 
3t4 inch 
3 y 2 inch 
3% inch 


39 lbs. 
45 lbs. 
62 lbs. 
79 lbs. 
103 lbs. 
146 lbs. 
































52 


AGITATION TANKS 


COLORADO 

IRON WORKS CO 



THE AKINS-KOTHWELL AGITATION TANK 














COLORADO 

IRON WORKS CO 


AGITATION TANKS. 


53 


The Akins-Rothwell Agitation Tank. 

(Patented) 

Iii this agitation tank are avoided all of the difficulties incident 
to the operation of agitators as heretofore designed. 

Agitation can be started after the charge has settled for any 
length of time, this being accomplished by means of the vertically 
movable central tube, which in practice is lowered when agitation is 
discontinued. Upon starting, the central tube is gradually raised and 
in a few minutes the entire contents of the tank can be brought into 
agitation. This feature has been proved thoroughly effective during 
about two years’ use. 

The tank is adapted to either compressed air agitation or agita¬ 
tion by means of a centrifugal pump. In the latter case, which is 
illustrated in the engraving herewith, the agitation tube is surrounded 
by a stationary tube having a rubber seat connection at the bottom 
and a trapped intake at the top, the pump suction being connected 
with the space between the two tubes. By this means none but the 
very finest solids pass through the pump and wear is practically 
eliminated. 

At the top of the agitation tube a cone-shaped distributing apron 
is placed, over which the pulp flows evenly. Beneath this apron, but 
above the surface of the charge is a cutting vane so designed as to 
continuously withdraw pulp without favoring coarse or fine, solid or 
liquid, the opening in this cutting vane being adjustable to make 
the outflow equal to the inflow. 

In the continuous method of agitation and circulation from tank 
to tank, the tops of all the tanks are placed substantially on a level, 
the circulation taking place through the cutting vanes. The dura¬ 
tion of the agitation is governed by the size and number of tanks 
used and the rate of inflow into the system. As the last mentioned 
factor is fixed the time of agitation determines the size and number 

of tanks. 

The tank can be used without the continuous circulation system 
and worked intermittently if desired. To agitate a charge under 
pressure, the tank is built with a dome top. The pump then being 
in a closed circuit, the pressure will balance, and agitation can be 

maintained without additional power. 

Our patents on this tank are broad, and cover the movable inner 
tube, the outer tube with trapped inlet to keep coarse sand out of the 
pump, the cutting vane for continuously removing pulp of the same 
composition as that undergoing agitation m the tank as well as “a 
plurality of tanks, means for agitating the material m the tanks, 
and a vane for continuously drawing a definite proportional quantity 
of liquid containing agitated solids from one tank and deluding 

it to the next tank.” 


54 


PULP THICKENERS 


COLORADO 

IRON WORKS CO 





T .V? ■- r- *t? 7.1 - 


..Jl. . VV JL . ^ 


AViyj; 


I p •. q q o 


USpsi 


THE ROTHWELL CONTINUOUS THICKENER 












































































































































































































COLOR ADO 

IRON WORKS CO 


PULP THICKENERS. 


55 


The Rothwell Continuous Thickener. 

(Patented in U. S. and Foreign Countries.) 

In the Rothwell Dewatering and Thickening Tank we present 
very decided improvements over anything heretofore used for like 
purposes. Its use results in great economy of space and a consid¬ 
erable saving in cost of foundations over round tanks of like capacity. 
It h as all the advantages of the cone tank for collecting the settled 
solids, to which is added a very large settling area, with slow-moving 
current for the settling of the very finest solids. A very high effi- 
cieney is secured by the length through which the liquid flows from 
the feed compartment to the overflow end, together with the greatly 
enhanced settling effect, produced by the inclined baffles. 

In the drawing the inflow is shown at A, between the vertical 
baffle B and the end of the tank. The top of this baffle is level with 
the top of the tank and extends about three-fourths of the depth of 
the main body of the tank, thus the whole feed passes to this depth 
and distributes into the first settling part C. The heaviest of the 
solids settle direct into the cone D, the lighter solids passing through 
the perforated plate forming the lower part of the baffle E, the top 
of which is about six inches below the top of the tank, so that a con¬ 
stant surface Aoav passes over the top of it and the inclined baffles. 
The very lightest of the suspended solids, when they settle into the 
spaces between the inclined baffles are removed from all disturbing 
influences. The effective settling area is thus equal to a tank of very 
much larger dimensions. The overflow weir is of soft metal, wood 
or belting, so that it can easily be brought to a uniform level. The 
clear overflow passes through the opening G in the collecting launder 
to the storage or other tank. 

The solids that settle to the floor of the main tank are moved 
to the collecting cone by the slowly-moving reciprocating conveyor II. 
The motion of the rake is forward on the bottom of the tank, at 
the end of the forward stroke it rises about three inches and returns 
to the other end of the stroke, when it descends to the floor of the 
tank again, thus slowly moving the solids that have settled toward 
the cone. 

The power required to move the rake is very small, about one- 
eighth horsepower being ample for regular work on the largest size 
tank. When double-end tanks are used, the method of operating is 
the same except that the feed is central over the cone. 

We issue a special pamphlet describing this machine. 


56 


SLIME FILTERS. 


COLOR ADO 

IRON WORKS CO 


The Portland Continuous Slime Filter. 

(Patent Pending.) 

The Portland filter has long since passed the experimental stage 
and its success has been so uniform that we unhesitatingly recom¬ 
mend it. Its work is in all respects equal to that of any other filter 
on similar ores and its advantages are such as to make it by far the 
most attractive filter to he obtained. 



TIIE PORTLAND CONTINUOUS SLIME FILTER. 


The great superiority of the revolving filter arises principally 
from the fact that it forms a thin cake, easily and thoroughly washed 
with a minimum amount of solution and water. A thin cake can 
be formed very rapidly and, being continuously removed as fast 
as formed, the capacity per unit of filtering area is very great. The 
time during which any section is submerged is only about three min¬ 
utes, as against three-quarters to two hours with submerged leaf 
filters forming a %-inch to %-inch cake. The time consumed in 





























COLOR ADO 

IRON WORKS CO 


SLIME FILTEES. 


57 


washing is equally favorable to the leaf filters, and, owing to the 
thicker cake, channeling takes place and the washing is less thorough. 

The continuous operation of the revolving filter is in itself a 
great advantage over machines of the leaf type, which are of neces¬ 
sity operated intermittently and require considerable attention. In 
strong contrast to this is the automatic action of the revolving drum 
type, which works continuously without attention, other than to look 
it over at intervals of two hours or so to see that everything is work¬ 
ing properly. The drum type of filter has a decided advantage over 
the submerged leaf type in point of space occupied for a given ton¬ 
nage capacity, and in initial cost of installation. 

The drum is divided into twenty-two independent sections, each 
covered with the filtering medium and connected by a pipe with the 
valve which controls the loading, washing and discharge of the cake. 
There are four ports in the valve, three under vacuum and one 
under compressed air. The latter is for the blow at discharge, while 
of the three vacuum ports, one is connected with the submerged por¬ 
tion of the drum, the next with the ascending side, where the wash¬ 
ing is done with weak solutions, and the third with the descending 
side, which is subjected to the water wash. The construction is the 
simplest conceivable, one pipe from each section serving for loading, 
washing with solution, washing with water and discharging, and 
but one pipe from the valve for each solution drawn off, and one for 
the blow. 

During revolution, nine sections are immersed in the pulp and 
the vacuum draws a thin, even cake on the filter medium. Each sec¬ 
tion of the drum, rising out of the pulp, soon meets the wash solu¬ 


tion coming down in a thin film from above. As it passes the top, 
this is changed to water, which is flowed on in a film which is so 
adjusted that it is all drawn through the cake just before it passes 
the point at which the suction is changed to the blow which disen¬ 
gages the cake. While all these solutions, air and vacuum pass 
through the single pipe connection with the filter section, the effect 
of the valve is to make a separate delivery of each solution so that 
it can be led to its appropriate tank. The cycle of loading, washing 
and discharging is therefore continuous and the entire operation 
from the maintenance of the pulp level in the tank to the final dis- 
charoe of the washed cake and delivery of the three solutions is 

O 

entirely automatic. 

When the preliminary grinding is done in water the machine is 
also used for the dewatering of the slime from thickening tanks, 
preparatory to treatment in cyanide solutions, when the continuous 
method of the treatment of an ore by the cyanide process is used. 

The filter is built 12 and 11 feet diameter and from 5 to 14 feet 
width of face as required for capacities up to 120 tons per 24 hours. 


58 


SAND AND SLIME FILTERS. 


COLOR ADO 

IRON WORKS CO 


The Rothwell Sand and Slime Filter. 

f Patented.^ 

The Rothwell horizontal pan sand and slime filter is designed to 
handle pulp carrying a large proportion of crystalloid or fine granu¬ 
lar product, such as it would be impossible to load on other filters. 
It is extremely simple in construction, automatic in operation and 
easily kept in continuous service without interruption for removal 
of the filter medium. 

The method of operation can readily he understood by refer¬ 
ence to the illustration, the machine as shown revolving clock-wise 



THE ROTIIWELL SAND AND SLIME FILTER. 

The pulp to be filtered is loaded into the pan passing under 
the feed distributor, to a depth of one or two inches. As soon as 
the pan has passed the loading point, the conduit leading from be¬ 
neath the filter medium to the central control valve registers with the 
first vacuum port, the degree of vacuum maintained in this port 
being determined by trial to leave a porous bed of solids. 

As soon as the liquid contained in the pulp is drawn through, 
the vacuum is cut out automatically and the pan loaded with wash 
solution or water, the conduit then registering with the second vacuum 
port through which this wash is drawn. A second wash is applied 















COLOR ADO 

IRON WORKS CO 


SAND AND SLIME FILTERS. 


59 


in like manner and drawn through the third vacuum port. The 
vacuum for these three ports is separately adjusted for the class of 
pulp handled, after which it remains fixed as long as conditions 
remain unchanged, separate delivery of the solution and washes be¬ 
ing made if desirable. 


After the pan has completed the loading, washing and drying 
parts of the cycle, it is tilted automatically to a position beyond the 
vertical, and air under pressure is admitted beneath the filter medium 
through the conduit and a port in the valves. This air pressure 
loosens the cake of solids and at the same time it is applied a wash¬ 
ing pressure port of the central valve registers with a separate con¬ 
duit and a spray of water or air is blown across the upper surface 
of the filter medium, clearing off anv solids not discharged bv the 
under blow. The pan now automatically resumes the horizontal posi¬ 
tion and passes under the feed distributor where it receives a fresh 
charge, the other pans having meanwhile gone through the same 
cycle of operations, the action is practically continuous. 

This filter should fill the want for a continuous machine capable 
of handling that large class of ore pulps in which the proportion of 
fine sands is too great to permit of loading satisfactorily on filters 
of the submerged leaf or revolving drum type. Like the Portland 
filter, its operation is free from the numerous disadvantages of the 


submerged leaf filters, particularly in the matters of attention re¬ 
quired and the pumping of large volumes of pulp, solutions and 
water which form such important items in the high cost of filtra¬ 
tion by the older methods. 

d 


The valve is mechanically the same as that which has proved 
so successful in the Portland filter, with such changes in the loca¬ 
tion of ports as are necessary to accomplish the special results desired. 
There is great latitude in the matter of adjustments to secure the 
most advantageous action at every point of the cycle and for this rea¬ 
son this machine has greater adaptability than any other. 

The pans are light and substantial and are interchangeable, and 
as renewals are confined entirely to the replacement of the filter 
medium, a few extra pans enable the machine to be maintained in 
the most efficient condition practically without interruption. The 
life of the filter medium depends on the pulp being handled, but 
will be as «reat as in any other filter, and as it is made up of cheap 

CJ d 

standard materials the cost is low. 

The power required for a 20-foot diameter machine making four 
to six revolutions per hour, is about one and one-half horse power 
and the capacity is very high. The driving mechanism, and, in fact, 
the entire machine, is extremely simple and there are no compli¬ 
cated or delicate adjustments to be made. Either the wet or dry 
vacuum can be used. 


60 


ZINC BOXES. 


COLORADO 
IRON WORKS CO 


Precipitation Boxes. 

For effecting precipitation by zinc shavings, boxes of various 
designs have been used, those here illustrated being such as have 
gained special favor among practical cyanide men. The superiority 
of steel over wood in the construction of zinc boxes is well settled, 
their freedom from leakage and permanence being strong points in 
their favor as well as the facility of making a thorough clean up. 
In addition to their other disadvantages, the wooden precipitation 
boxes absorb more or less of the values in solution and their crevices 
offer lodgement for precipitate. 



STANDABD STEEL ZINC BOX. 

Our standard steel precipitation box is shown above. This is 
used in medium size and large plants, the number depending upon 
the capacity required. The solution enters the box through the nar- 
roAv compartment shown nearest the observer in the illustration, and 
rises through the first wide compartment. The overflow from each 
large compartment is into a narrow one which directs the solution 
beneath the screen of the larger compartment next following, the 
barren solution finally rising in a narrow compartment at the farther 
end and leaving the box through pipes. 

The holes leading to the pipe below the box are closed bv rubber 
stoppers which are removed at the clean up and the precipitate 
flushed into a tank. 

The total weight of this zinc box is about 1,000 pounds, and the 






COLOR ADO 

IRON WORKS CO 


ZINC BOXES. 


61 


capacity of that part of each large compartment which is filled with 
zinc shavings, about cubic feet. 

The Webb type of zinc box is shown below. In this box it is 
sought to take advantage of increased precipitating power due to 
electrolytic action arising from a carbon-zinc couple, brought about 
by filling the compartments alternately with charcoal and with zinc 
shavings. 

Referring: to the illustration, the solution enters at the farther 
end, flowing downward through charcoal and being directed upward 
through the next compartment containing zinc shavings, this being 
continued throughout the length of the box, the barren solution leav¬ 
ing through a pipe near the top of the lower end. 



Of the twelve compartments, six, for charcoal, have a capacity 
of 11/ 2 cubic feet each, and six, for zinc shavings, have a capacity of 
1% cubic feet each. In many cases where boxes of this type are 
used, all the compartments are filled with zinc shavings, but this 
offers the disadvantage of passing the solution downward through the 
zinc in half of the compartments and the box then becomes but an 

inferior substitute for our standard box. . 

The clean up is made by removing the rubber stoppers which are 

shown within the trough at the side, and flushing out the precipi a e 
through the trough and pipe in its end. Weight about 800 pounds. 







































































ZINC BOXES. 


COLORADO 

IRON WORKS CO 


Individual zinc boxes are the most convenient for small plants. 


but sizes larger than those here shown sometimes are used in large in- 

O 

stallations. Only the uppermost boxes are cleaned up, those occupy¬ 
ing the middle and lower positions being advanced to the upper end 



and the boxes which have 
been cleaned up and filled 
with fresh zinc placed at 
the lower end of the series. 

By this means clean zinc is 
brought into contact with 
the weakest solution, and 
while this is also accom¬ 
plished in boxes of the mul¬ 
tiple compartment form, 
by transferrins* zinc from 
lower to upper compart¬ 
ments, it is necessary to 
handle the contents of all 
the compartments. How¬ 
ever, this presents the op¬ 
portunity to place a layer of fresh zinc at the bottom before return¬ 
ing the old zinc, which largely prevents the “shorts” from passing 
through the screen. 


HOUND INDIVIDUAL ZINC BOXES. 



In the round boxes, the 
solution is led below the 
false bottom by a pipe pass¬ 
ing down the center, and 
passes upward through the 
zinc shavings, discharging 
through a pipe in the side 
near the top. In service, 
the pipes are joined by un¬ 
ions as shown. The capac¬ 
ity of the round box illus- 

*y 

trated is about 13/5 cubic 
feet and the weight about 
55 pounds. 

The square boxes are of 
simple construction and require no explanation. The one illustrated 
has about one cubic foot capacity and weighs about 30 pounds. 


SQUARE INDIVIDUAL ZINC BOXES. 












COLOR ADO 

IRON WORKS CO 


SLAGGING ANI> BULLION MOULDS. 


63 


Bullion Moulds. 

Our bullion moulds are made of a fine grade of close-grained 
iron, free from imperfections of all kinds, are trimmed out and have 
smooth and true surfaces. 



SIZES AND CAPACITIES OF BULLION MOULDS 


Length 

Width 

Depth 

Capacity in Ounces 

Weight 

Inches 

Inches 

Inches 

Gold 

Silver 

Lbs. 

3V 2 

1 

1 

20 

10 

2 

3y 2 

iy 2 

iy 2 

50 

25 

214 

4 

2 

2 

100 

56 

4% 

5V 2 

2% 

2% 

250 

140 

8 

ey 2 

314 

314 

500 

275 

14 

9 

3% 

3% 

1,000 

550 

25 

n 

4% 

4% 

2,000 

1,100 

50 

iiy 2 

514 

4y 2 

2,500 

1,350 

55 

12 

7 

6 

5,000 

3,000 

110 


Conical Slagging Moulds. 



These moulds are made very heavy 
and are finished inside. They are about 
14 inches in diameter and 12 inches 
high over all. The base and rim are 

o 

the same diameter, so they can be rolled 
about on the floor. The capacity when 
filled within one-half inch of the top is 
somewhat over a gallon, and the weight 
is 200 pounds. 





























64 


TANKS. 


COLORADO 

IRON WORKS CO 


Steel Tanks. 

The advantages of steel tanks over wooden tanks are so many 
and important that they greatly outweigh any considerations of rela¬ 
tive first cost. We make steel tanks of all kinds used in cyanide 
work, including lead lined tanks for acid treatment. We manufac¬ 
ture all the special fittings and attachments, some of which are illus¬ 
trated and described in this catalogue, which enter into the completed 
tanks as used in the application of the cyanide process to ores. Our 
experience in this line has been very large and our familiarity with 
all the requirements enables us so to design and construct them as 
most fully to attain the desired results in operation. 

On the opposite page we present a table showing the capacities 
of tanks of various sizes, hoping these data may be of assistance in 
making preliminary estimates of the sizes and number of tanks re¬ 
quired, as well as in the operation of the plant. 

The figures given are for U. S. gallons of 231 cubic inches and 
short tons of 2,000 pounds. For imperial gallons the figures should 
be multiplied by .8333, and for long tons of 2,240 pounds, the fig¬ 
ures for short tons should be multiplied by .8928. The figures rep¬ 
resenting tons of sand are based on 25 cubic feet per ton, which is 
arbitrary, as the capacity of tanks will vary from this if the specific 
gravity differs from that which is assumed, and will also vary be- 
tween wide limits according to the manner of charging, whether wet, 
moist or dry. 

The capacities of sizes other than those listed can readily be 
ascertained by remembering that the areas vary as the square of the 
diameters; that is, a tank having a diameter twice as great as a given 
tank will have four times the capacity. The figures representing 
cubic feet also equal the area of the bottom of the tank, in square 
feet. In estimating the capacity of a sand leaching tank, about six 
inches should be allowed for the filter bottom and about six inches 
for the rim of the tank to extend above the point to which it is in¬ 
tended to be filled. 

The capacity of a conical tank is one-third that of a cylindrical 
tank of the same diameter and height; therefore, to find the total 
capacity of a cone-bottom tank, take the capacity of the cylindrical 
part from the table and add one-tliird of the capacity of a cylindrical 
tank having the diameter of the largest part of the cone and a height 
equal to the perpendicular distance from the rim to the apex. 


COLORADO 

IRON WORKS CO 


TABLES. 


G5 


Capacities of Tanks. 


Dian 

Ft. 

teter 

PER FOOT DEPTH 

Per Inch 
Depth 
Tons 
Water 

Diameter 

Ft. In. 

In. 

Cubic Feet 

Gallons 

Tons Water 

L 

Tons Sand* 

4 

0 

12.57 

93.97 

.39 

.50 

.033 

4 

0 

4 

6 

15.90 

118.93 

.50 

.64 

.041 

4 

6 

5 

0 

19.64 

146.83 

.61 

.79 

.051 

5 

0 

5 

6 

23.76 

177.67 

.74 

.95 

.062 

5 

6 

6 

0 

28.27 

211.44 

.88 

1.13 

.074 

6 

0 

6 

6 

33.18 

248.15 

1.03 

1.33 

.086 

6 

6 

7 

0 

38.48 

287.80 

1.20 

1.54 

.100 

7 

0 

7 

6 

44.18 

330.38 

1.38 

1.77 

.115 

7 

6 

8 

0 

50.27 

375.90 

1.57 

2.01 

.131 

8 

0 

8 

6 

56.75 

424.36 

1.77 

2.27 

.149 

8 

6 

9 

0 

63.62 

475.75 

1.98 

2.55 

.165 

9 

0 

9 

6 

70.88 

530.08 

2.22 

2.84 

.185 

9 

6 

10 

0 

78.54 

587.35 

2.46 

3.14 

.205 

10 

0 

10 

6 

86.59 

647.55 

2.71 

3.46 

.225 

10 

6 

11 

0 

95.03 

710.69 

2.97 

3.80 

.248 

11 

0 

11 

6 

103.87 

776.77 

3.25 

4.16 

.271 

11 

6 

12 

0 

113.10 

845.18 

3.54 

4.52 

.295 

12 

0 

13 

0 

132.73 

992.62 

4.14 

5.31 

.345 

13 

0 

14 

0 

153.94 

1,151.21 

4.81 

6.16 

.401 

14 

0 

15 

0 

176.72 

1,321.54 

5.52 

7.07 

.460 

15 

0 

16 

0 

201.06 

1,503.62 

6.28 

8.04 

.524 

16 

0 

17 

0 

226.98 

1,697.45 

7.09 

9.08 

.591 

17 

0 

18 

0 

254.47 

1,903.02 

7.92 

10.18 

.660 

18 

0 

19 

0 

283.53 

2,120.34 

8.86 

11.34 

.738 

19 

0 

20 

0 

314.16 

2,349.41 

9.82 

12.57 

.818 

20 

0 

21 

0 

346.36 

2,590.22 

10.82 

13.85 

.902 

21 

0 

22 

0 

380.13 

2,842.79 

11.88 

15.21 

.990 

22 

0 

23 

0 

415.48 

3,107.10 

12.98 

16.62 

1.082 

23 

0 

24 

0 

452.39 

3,383.15 

14.14 

18.10 

1.178 

24 

0 

25 

0 

490.88 

3,670.95 

15.34 

19.64 

1.278 

25 

0 

26 

0 

530.93 

3,970.50 

16.56 

21.24 

1.380 

26 

0 

27 

0 

572.56 

4,281.80 

17.89 

22.90 

1.491 

27 

0 

28 

0 

615.75 

4,604.85 

19.24 

24.63 

1.604 

28 

0 

29 

0 

660.52 

4,939.64 

20.64 

26.42 

1.720 

29 

0 

30 

0 

706.86 

5,286.18 

22.09 

28.27 

1.841 

30 

0 

32 

0 

804.25 

6,014.48 

25.13 

32.17 

2.094 

32 

0 

34 

0 

907.92 

6,789.80 

28.37 

36.32 

2.364 

34 

0 

36 

0 

1,017.88 

7,612.08 

31.69 

40.72 

2.641 

36 

0 

38 

0 

1,134.12 

8,481.36 

35.44 

45.36 

2.953 

38 

0 

40 

0 

1,256.64 

9,397.64 

39.27 

50.27 

3.273 

40 

0 

42 

0 

1,385.45 

10,360.88 

43.30 

55.42 

3.608 

42 

0 

44 

0 

1,520.53 

11,371.16 

47.52 

60.82 

3.960 

44 

0 

46 

0 

1,661.91 

12,428.40 

51.94 

66.48 

4.328 

46 

0 

48 

0 

1,809.56 

13,532.60 

56.55 

72.38 

4.712 

48 

0 

50 

0 

1,963.50 

14,683.80 

61.36 

78.54 

5.113 

50 

0 


* Figures for tons of sand are based on 25 cubic teet per ton 















































6G 


TABLES. 


COLORADO 

IRON WORKS CO 


Equivalent Rates of Flow of Water. 


Tons 

per 

24 Hours 

Tons 

per 

Hour 

Cu. Feet 
per 

Hour 

Cu. Feet 
per 

Minute 

Gallons 

per 

Hour 

Gallons 

per 

Minute 

1 

.042 

1.337 

.0223 

10 

.1667 

2 

.083 

2.674 

.0446 

20 

.3333 

3 

.125 

4.010 

.0668 

30 

.5000 

4 

.167 

5.347 

.0891 

40 

.6667 

5 

.208 

6.684 

.1114 

50 

.8333 

6 

.250 

8.021 

.1337 

60 

1,000 

7 

.292 

9.358 

.1560 

70 

1.167 

8 

.333 

10.69 

.1782 

80 

1.333 

9 

.375 

12.03 

.2005 

90 

1.500 

10 

.417 

13.37 

.2228 

100 

1.667 

20 

.833 

26.74 

.4456 

200 

3.333 

30 

1.25 

40.10 

.6684 

300 

5.000 

40 

1.67 

53.47 

.8912 

400 

6.667 

50 

2.08 

66.84 

1.114 

500 

8.333 

60 

2.50 

80.21 

1.337 

600 

10.00 

70 

2.92 

93.58 

1.560 

700 

11.67 

80 

3.33 

106.9 

1.782 

800 

13.33 

90 

3.75 

120.3 

2.005 

900 

15.00 

100 

4.17 

133.7 

2.228 

1000 

16.67 

200 

8.33 

267.4 

4.456 

2000 

33.33 

300 

12.5 

401.0 

6.684 

3000 

50.00 

400 

16.7 

534.7 

8.912 

4000 

66.67 

500 

20.8 

668.4 

11.14 

5000 

83.33 

600 

25.0 

802.1 

13.37 

6000 

100.0 

700 

29.2 

935.8 

15.60 

7000 

116.7 

800 

33.3 

1069. 

17.82 

8000 

133.3 

900 

37.5 

1203. 

20.05 

9000 

150.0 

1000 

41.7 

1337. 

22.28 

10000 

166.7 


EXAMPLE—To find the flow in gallons per minute equal to 85 tons per day, 
add the figures for 80 and for 5 tons thus: 13.33+.833=14.16 gallons per min¬ 
ute. 

All figures are based on U. S. gallons of 231 cubic inches and tons of 2,000 
pounds. 

Tons per day-f-6=gallons per minute. 



























TABLES. 


67 


COLORADO 

IRON WORKS CO 


Equivalent Rates of Flow of Water. 


Gallons 

per 

Minute 

Gallons 

per 

Hour 

Cu. Feet 
per 

Minute 

Cu. Feet 
per 

Hour 

Tons 

per 

Hour 

Tons 

per 

24 Hours 

1 

60 

.134 

8.021 

.25 

6 

2 

120 

.267 

16.04 

.50 

12 

3 

180 

.401 

24.06 

.75 

18 

4 

240 

.535 

32.08 

1.00 

24 

5 

300 

.668 

40.10 

1.25 

30 

6 

360 

.802 

48.13 

1.50 

36 

7 

420 

.936 

56.15 

1.75 

42 

8 

480 

1.069 

64.17 

2.00 

48 

9 

540 

1.203 

72.18 

2.25 

54 

10 

600 

1.337 

80.21 

2.50 

60 

20 

1200 

2.674 

160.4 

5.00 

120 

30 

1800 

4.010 

240.6 

7.50 

180 

40 

2400 

5.347 

320.8 

10.0 

240 

50 

3000 

6.684 

401.0 

12.5 

300 

60 

3600 

8.021 

481.3 

15.0 

360 

70 

4200 

9.358 

561.5 

17.5 

420 

80 

4800 

10.69 

641.7 

20.0 

480 

90 

5400 

12.03 

721.8 

22.5 

540 

100 

6000 

13.37 

802.1 

25.0 

600 

200 

12000 

26.74 

1604. 

50.0 

1200 

300 

18000 

40.10 

2406. 

75.0 

1800 

400 

24000 

53.47 

3208. 

100. 

2400 

500 

30000 

66.84 

4010. 

125. 

3000 

600 

36000 

80.21 

4812. 

150. 

3600 

700 

42000 

93.58 

5615. 

175. 

4200 

800 

48000 

106.9 

6417. 

200. 

4800 

900 

54000 

120.3 

7218. 

225. 

5400 

1000 

60000 

133.7 

8021. 

250. 

6000 


EXAMPLE—To find the number of tons per day equivalent to 73 gallons 
per minute, add the figures for 70 and for 3, thus: 420 + lS=43S tons per ‘lay. 

All figures are based on U. S. gallons of 231 cubic inches and tons of 2,000 


pounds. 

Gallons per minuteX G=tons per day. 



































68 


TABLES. 


COLORADO 

IRON WORKS CO 


Slime Density Relations/ 


The table is based on the percentage of solid in the slime, oppo¬ 
site which is given the ratio of solid to liquid. The numbers head¬ 
ing the double columns following, are the specific gravities of the 
dry solid (that of water being taken as unity). The columns headed 
S. G. show the specific gravities of the slime, that of water being 
taken as 1000; that is, the figures show directly the weight of a liter 
of slime in grams. The columns headed Yol. show the number of 
cubic feet of the slime in one ton of 2000 pounds. 

The specific gravities of solids chosen will probably cover the 
range of slimes ordinarily met with and the intervals are sufiicientlv 
small to admit of interpolation without appreciable error. The last 
column (4.50) is a hypothetical concentrate and is the specific grav¬ 
ity of a mixture of 80 per cent, pyrite and 20 per cent, quartz. The 
average specific gravity of working cyanide solutions is so small as to 
be negligible. 

The table is convenient for ascertaining the amount of solid and 

O 


of solution in slime pulps from the number of cubic feet, determined 
by rod or float, in the tank; and specific gravity of the slime, deter¬ 
mined by taking the weight of a liter or by a specific gravity indi¬ 
cator in the tank. It is useful in calculations for ascertaining the 
amount of solution to be abstracted or added in thickening and dibit- 
ing, for correcting the strength of the solutions, for checking tonnage 
and for other purposes. 

Assume that in a plant in which the specific gravity of the solid 
is 2.7, a tank is shown, by the depth of pulp in it, to contain 3530 
cubic feet of pulp, a liter of which weighs 1223 grams. From the 
table it is found that the specific gravity 1223 corresponds to 26.16 
cubic feet per ton and to 29 per cent, solid. The weight of pulp, 
therefore, is 3530-1-26.16=135 tons and the weight of solids 135 
X0.29=39.15 tons. The weight of solution is, by difference, 95.85 
tons. If the solution titrates 1.05 pounds cyanide per ton and it is 
desired to bring the strength up to 2.5 pounds per ton, we have 2.5— 
1.05=1.45 pounds cyanide to be added per ton. Therefore, 95.85 
X 1.45=139 pounds cyanide to be added to the tank. 

The table is useful in determining the sizes of tanks necessary 
for any given capacities. Thus, if it is desired to agitate 50 tons of 
dry slime (specific gravity of solid 2.6) with three parts solution, the 
table shows this to contain 25 per cent, solids and to have a volume of 
27.08 cubic feet per ton; therefore, 50-^-0.25=200 tons of slimeX 
27.08=5416 cubic feet, the required effective working capacity of 
the tank, to which an amount must be added to secure the desired 
height of curb above the charge. 


* Metallurgical and Chemical Engineering. June, 1912. 












■nt. 

lids 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

3 4 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

51 

52 

53 

54 

55 

56 

57 

58 

59 

60 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 


TABLES 


69 


Slime Density Relations. 


Ratio of 
Solids to 
Solution. 


1:19. 

1:15. 

1:13. 

1 : 11 . 

1 : 10 . 


1 : 
1 : 
1: 
1 : 
1: 
1: 
1 : 
1: 
1 : 
1 : 
1: 
1 : 
1: 
1: 
1 : 
1: 
1: 
1 : 
1: 
1: 
1: 
1 : 
1 : 
1: 
1: 
1: 
1: 
1: 
1: 
1: 
1 : 
1: 
1 : 
1 : 
1 : 
1 : 
1 : 
1: 
1: 
1: 
1 
1 
1 
1 : 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1: 
1 
1 
1 
1 
1 
1 


9. 
8 . 
7. 
6 . 
6 . 
5. 
5. 
4. 
4. 
4. 
4. 
3. 
3. 
3. 
3. 
3. 
2 . 
2 . 
2 . 
2 . 
2 . 
2 . 
2 . 
2 . 
1. 
1 . 
1. 
1. 
1. 
1 . 
1 . 
1. 
1. 
1 . 
1. 
1 . 
1 . 
1. 
1. 
1. 
1. 
0. 
0 . 
0 . 
0 . 
0. 
0 . 
0 . 
0 
0 . 
0 
0, 
0 . 
0 
0 . 
0 
0 
0 
0 
0 
0 


000 

667 

286 

500 

111 

000 

091 

333 

692 


Specific Gravity of Pulp and Volume of One Ton in Cubic 
Feet, for Slimes Containing- Solids of Dif¬ 
ferent Specific Gravities. 


545 


2.50 

2.60 

2. 

70 

2. 

80 

2.90 

S.G. 

Vol. 

S.G. 

Vol. 

S.G. 

Vol. 

S.G. 

Vol. 

S.G. 

Vol. 

1031 

31.03 

1032 

31.01 

1032 

31.01 

1033 

30.97 

1034 

30.95 

1037 

30.85 

1036 

30.82 

1039 

30.79 

1040 

30.76 

1041 

30.74 

1044 

30.66 

1045 

30.621 

1046 

30.59 

1047 

30.56 

1048 

30.53 

| 1050 

30.46 

1052 

30.43 

1053 

30.39 

1055 

30.36 

1055 

30.32 

1057 

30.27 

1059 

30.23 

1060 

30.19 

1061 

30.15 

1063 

30.11 

1064 

30.OS 

1065 

30.03 

1067 

29.99 

1068 

29.95 

1070 

29.90 

1071 

29.88 

1073 

29.83 

1074 

29.79 

1076 

29.74 

1078 

29.69 

1078 

29.70 

1080 

29.64 

1082 

29.59 

1083 

29.53 

10851 

29.4S 

1085 

29.50 

108 7 

29.44 

1089 

29.39 

1091 

29.33 

1093 

29.27 

1092 

29.31 

1094 

29.24 

1097 

29.19 

1099 

29.12 

11011 

29.06 

1099 

29 . IS 

1102 

29.05 

1104 

28.99 

1107 

2S.91 

1109 

28.85 

1106 

28.93 

1109 

28.85 

1112 

28.78 

1115 

28.71 

11171 

28.65 

1114 

28.74 

1117 

28.65 

1119 

28.58 

1123 

2S . 50 

1125 

28.44 

1121 

28.54 

1125 

28.45 

1128 

28.38 

1131 

28.30 

11341 

28.23 

1129 

28.35 

1133 

28.26 

1136 

28.18 

1139 

28.09 

11421 

28.02 

1136 

28.17 

1140 

28.06 

1144 

27.98 

1147 

27.89 

1151 

27.81 

1144 

27.97 

114S 

27.87 

1152 

27.77 

1156 

27.68 

1159 

27.60 

1152 

27.78 

1157 

27.67 

1161 

27.57 

1165 

27.47 

1168 

27.39 

1160 

27.58 

1165 

27.47 

1169 

27.37 

1174 

27.27 

1177 

27.18 

116S 

27.39 

1173 

27.27 

1178 

27.17 

1182 

27.06 

1186 

26.97 

1176 

27.21 

1182 

27.08 

1187 

26.97 

1191 

26.85 

1195 

26.76 

1185 

27.01 

1190 

26.88 

1195 

26.77 

1201 

26.65 

1205 

26.55 

1193 

26.82 

1199 

26.68 

1205 

26.56 

1210 

26.44 

1215 

26.84 

1202 

26.62 

1209 

26.49 

1214 

26.36 

1220 

26.24 

1224 

26.13 

1211 

26.43 

1217 

26.29 

1223 

26.16 

1229 

26.03 

1234 

25.92 

1220 

26.24 

1226 

26.10 

1233 

25.95 

1239 

25.83 

1244 

25.71 

1229 

26.05 

1236 

25.90 

1242 

25.75 

1249 

25.63 

1255 

25.50 

1238 

25.86 

1245 

25.70 | 

1252 

25.55 

1259 

25.42 

' 1265 

25.29 

1247 

25.66 

1255 

25.50 

1262 

25.35 

1269 

25.21 

1276 

25.08 

1256 

25.47 

1264 

25.31 

1272 

25.15 

1279 

25.01 

1287 

24.87 

1266 

25.28 

1274 

25.12 

12S3 

24.95 

1290 

24.80 

1298 

24.66 

1276 

25.09 

1284 

24.91 

1293 

24.75 

1301 

24.60 

| 1309 

24.45 

1285 

24.90 

1295 

24.71 

1304 

24.55 

1312 

24.39 

1320 

24.24 

1295 

24.70 

1305 

24.52 

1314 

24.35 

1323 

24.19 

1332 

24.03 

1305 

24.51 

1316 

24.32 

1326 

24.14 

1335 

23.98 

1343 

23.82 

1316 

24.32 

1326 

24.13 

1336 

23.95 

1346 

23.77 

1355 

23.61 

1326 

24.13 

1337 

23.93 

1348 

23.74 

1357 

23.57 

1367 

23.40 

1337 

23.94 

1 1348 

23.73 

1359 

23.55 

1370 

23.36 

1380 

23.19 

1348 

23.74 

1359 

23.53 

1371 

23.34 

1382 

23.16 

1392 

22.99 

1359 

23.55 

1372 

23.33 

1383 

23.15 

1395 

22.95 

1405 

122.78 

1370 

23.36 

1383 

23.14 

1395 

22.94 

1407 

22.74 

1418 

22.57 

i 13S1 

23.17 

1395 

22.94 

1408 

22.73 

1420 

22.54 

143 2 

j 22.36 

3 1393 

22.98 

1407 

22.75 

1420 

22.54 

1433 

22.33 

1445 

22.15 

1404 

22.78 

1419 

22.55 

1433 

22.33 

1446 

22.12 

1458 

121.94 

1416 

22.59 

1431 

22.35 

1446 

22.13 

1460 

21.92 

1473 

21.73 

) 1429 

22.39 

1444 

22.15 

1460 

21.92 

1473 

21.71 

1487 

21.52 

1441 

22.21 

1458 

21.96 

1473 

21.72 

1488 

21.51 

1502 

21.31 

1 1453 

22.02 

1471 

21.76 

1487 

21.52 

1502 

21 .30 

1517 

j 21.1C 

1 1466 

21.82 

1484 

21 .56 

1501 

21 . 32 

1516 

21.10 

1532 

20. SS 

2 1479 

21.63 

1498 

21 .36 

1515 

21.12 

1532 

20.89 

1548 

20.6£ 

i 1493 

21.44 

1512 

21 .17 

1530 

20.92 

1547 

20.69 

1564 

20.4/ 

1 1506 

21.25 

1526 

20.97 

1545 

20.72 

1563 

20.48 

1580 

20.2f 

t 1520 

21 .06 

1540 

20.77 

15 60 

20.51 

1579 

20.27 

1596 

20.0E 

1 1534 

20.86 

1555 

20.58 

1574 

20.31 

1595 

20.07 

1613 

19.81 

! 1548 

20.67 

1572 

20.38 

1591 

20.11 

1611 

19.86 

1629 

19.65 

r 1563 

20.48 

1585 

20.18 

1607 

19.91 

1628 

19.66 

1645 

19.42 

) 1577 

20.29 

1601 

19.98 

1 623 

19.71 

1645 

19.45 

1664 

19.21 

1 1592 

20.10 

1617 

19.79 

1641 

19.51 

1662 

19.25 

1683 

19.0( 

7 1608 

19.90 

1633 

19.59 

1 65 7 

19.30 

1681 

19.04 

1703 

18.7J 

} 1623 

19.71 

1 650 

19.40 

1675 

19.10 

1698 

18.94 

1723 

18.5? 

3 1639 

19.52 

1667 

19.20 

1692 

18.90 

1718 

18.73 

1742 

18.3 r 

5 1656 

19.32 

1 684 

19.00 

1 711 

18.70 

1738 

18.53 

1762 

18. If 

1 1672 

19.14 

1701 

18.80 

1730 

18.50 

1757 

18.32 

1783 

1 7.9f 

1689 

18.94 

1719 

18.61 

1 749 

18.30 

1776 

1 S . 11 

1 803 

17.7- 

1 170 6 

18.75 

1738 

18.41 

1768 

18.10 

1797 

17.81 

1825 

17 . 5 : 

1 1724 

18.56 

1757 

18.21 

1786 

17.90 

1818 

17.60 

1847 

1 

17.32 












































































































TO 


TABLES 


COLOR ADO 

IRON WORKS CO 


Slime Density Relations. 


n- 

Specific Gravity of Pulp and Volume of One Ton in Cubic 
Feet, for Slimes Containing Solids of Dif¬ 
ferent Specific Gravities. 


Cent. 

Solids. 

Solids to 
Solution. 

3.00 

r 

3. 

10 

3.20 

3.30 

*4.50 

S.G. 

Vol. 

S.G. 

Vol. 

J 

S.G. 

Vol. 

S.G. 

Vol. 

S.G. 

Vol. 

5 

1:19.000 

1035 

30.93 

1035 

30.92 

1036 

30.90 

1036 

30.89 

1040 

30.76 

6 

1:15.667 

1042 

30.72 

1042 

30.70 

1043 

30.68 

1043 

30.66 

1049 

30.51 

7 

1:13.286 

1049 

30.51 

1049 

30.48 

1050 

30.46 

1051 

30.43 

1058 

30.26 

8 

1:11.500 

1056 

30.30 

1057 

30.27 

1058 

30.24 

1059 

30.21 

1067 

30.01 

9 

1 :10.111 

1064 

30.09 

1065 

30.05 

1066 

30.02 

1067 

29.99 

1075 

29.76 

10 

1: 9.000 

1071 

29.87 

1072 

29.83 

1074 

29.80 

1075 

29.77 

1084 

29.51 

11 

1: 8.091 

1078 

29.65 

1080 

29.61 

1082 

29.58 

1083 

29.54 

1093 

29.26 

12 

1: 7.333 

1087 

29.44 

1088 

29.40 

1090 

29.36 

1091 

29.32 

1102 

29.01 

13 

1: 6.692 

1095 

29.23 

1096 

29.18 

1098 

29.14 

1099 

29.10 

1112 

28.76 

14 

1: 6.144 

1103 

29.01 

1105 

28.96 

1106 

28.92 

1108 

28.88 

1122 

28.52 

15 

1: 5.667 

1111 

28.80 

1113 

28.74 

1115 

28.70 

1117 

28.66 

1132 

28.27 

16 

1: 5.250 

| 1119 

28.59 

1122 

28.53 

1124 

28.48 

1125 

28.43 

1142 

28.02 

17 

1: 4.882 

1128 

28.37 

1130 

28.31 

1132 

28.26 

1134 

28.21 

1152 

27.77 

18 

1: 4.556 

1136 

28.16 

1139 

28.10 

1141 

28.04 

1143 

27.99 

1163 

27.52 

19 

1: 4.263 

1145 

27.95 

1148 

27.88 

1150 

27.82 

1153 

27.76 

1173 

27.27 

20 

1: 4.000 

1154 

27.73 

1157 

27.66 

1159 

27.60 

1162 

27.54 

1184 

27.02 

21 

1: 3.762 

1163 

27.52 

1166 

27.44 

1169 

27.38 

1171 

27.32 

1194 

26.77 

22 

1: 3.545 

1172 

27.31 

1175 

27.23 

1178 

27.16 

1181 

27.09 

1206 

26.52 

23 

1: 3.348 

1181 

27.09 

1184 

27.01 

1188 

26.94 

1191 

26.87 

1218 

26.28 

24 

1: 3.167 

1190 

26.88 

1194 

26.79 

1198 

26.72 

1201 

26.65 

1230 

26.03 

25 

1: 3.000 

1200 

26.67 

1204 

26.58 

1208 

26.50 

1211 

26.42 

1241 

25.78 

26 

1: 2.846 

1210 

26.45 

1214 

26.37 

1218 

26.28 

1222 

26.20 

1253 

25.53 

27 

1: 2.704 

1220 

26.24 

1224 

26.15 

1228 

26.06 

1232 

25.98 

1266 

25.28 

28 

1: 2.571 

1230 

26.03 

1234 

25.93 

1239 

25.84 

1242 

25.75 

1278 

25.03 

29 

1: 2.448 

1240 

25.81 

1244 

25.71 

1249 

25.62 

1253 

25.53 

1291 

24.78 

30 

1: 2.333 

1250 

25.60 

1255 

25.50 

1260 

25.40 

1264 

25.31 

1304 

24.53 

31 

1 : 2.226 

1261 

25.39 

1266 

25.28 

1271 

25.18 

1275 

25.08 

1317 

24.28 

32 

1 : 2.125 

1271 

25.17 

1277 

25.06 

1282 

24.96 

1287 

24.86 

1331 

24.04 

33 

1: 2.030 

1282 

24.96 

1288 

24.85 

1293 

24.74 

1299 

24.64 

1345 

23.79 

34 

1: 1.940 

1293 

24.75 

1299 

24.63 

1305 

24.52 

1311 

24.41 

1359 

23.54 

35 

1: 1.857 

1304 

24.53 

1310 

24.41 

1317 

24.30 

1323 

24.19 

1374 

23.28 

36 

1: 1.778 

1316 

24.32 

1322 

24.19 

1329 

24.08 

1335 

23.97 

1389 

23.04 

37 

1: 1.703 

1328 

24.11 

1334 

23.98 

1341 

23.86 

1347 

23.75 

1404 

22.79 

38 

1: 1.632 

1340 

23.89 

1346 

23.76 

1353 

23.64 

1360 

23.52 

1420 

22.54 

39 

1: 1.564 

1351 

23.68 

] 358 

23.55 

1366 

23.42 

1373 

23.30 

1435 

22.29 

40 

1: 1.500 

1363 

23.47 

1371 

23.33 

1379 

23.20 

1387 

23.08 

1451 

22.04 

41 

1: 1.439 

1376 

23.26 

1384 

23.11 

1393 

22.98 j 

1400 

22.85 

1468 

21 . 79 

42 

1: 1.381 

1389 

23.04 

1397 

22.89 

1406 

22.76 

1414 

22.63 

1485 

21.55 

43 

1: 1.326! 

1402 

22.83 

1411 

22.68 

1419 

22.54 

1428 

22.41 

1502 

21 . 30 

44 

1: 1.273 

1415 

22.61 

1425 

22.46 

1433 

22.32 

1442 

22.18 

1519 

21.05 

45 

1 : 1.222 

1429 

22.40 

1438 

22.24 

1447 

22.10 

1456 

21.96 

1538 

20.80 

46 

1: 1.174 

1443 

22.19 

1452 

22.02 

1462 

21.88 

1471 

21.74 

1557 

20.55 

47 

1 : 1.128 

1457 

21.97 

1467 

21 .81 

1477 

21.66 

1487 

21.51 

1576 

20.30 

48 

1 : 1.083 

1471 

21.76 

1483 

21.60 

1493 

21.44 

1503 

21.29 

1595 

20.05 

49 

1: 1.041 

14S5 

21.55 

1497 

21.38 

1508 

21.22 

1519 

21.07 

1615 

19.81 

50 

1 : 1.0001 

1500 

21.33 

1512 

21.16 

1524 

21.00 

1535 

20.85 

1637 

19.56 

51 

1: 0.961 

1515 

21.12 

1528 

20.94 

1540 

20.78 

1551 

20.62 

1658 

19.31 

52 

1: 0.923| 

1531 

20.91 

1544 

20.73 

1556 

20.56 

1568 

20.40 

1679 

19.06 

53 . 

1: 0.887 

1547 

20.69 

1560 

20.51 

1573 

20.34 

1585 

20.18 

1700 

18.81 

54 

1: 0.852{ 

1563 

20.48 

1577 

20.29 

1590 

20.12 

1603 

19.96 

17241 

18.56 

55 

1 : 0.809 

1579 

20.27 

1594 

20.08 

1608 

19.90 

1621 

19.73 

1748! 

18.31 

56 

1: 0.786 

1596 

20.05 

1611 

19.87 

1626 

19.68 

1640 

19.51 

1772 

18.06 

57 

1: 0.7541 

1613 

19.84 

1628 

19.65 

1645 

19.46 

1659 

19.29 

1796 

17.81 

58 

1: 0.724 

1631 

19.63 

1646 

19.43 

1663 

19.24 

1678 

19.06 

1822 

17.56 

59 

1: 0.695 

1649 

19.41 

1665 J 

19.21 

1682 

19.02 

1697 

18.84 

1848 

17.32 

60 

1: 0.667 

1667 

19.20 

1684 

19.00 

1702 

18.80 

1718 

IS.62 

1875 

17.07 

61 

1: 0.639 

1686 

18.99 

1704 

18.78 

1722 j 

18.58 

1739 

18.39 

1903! 

16.82 

62 

1: 0.613 

1705 

18.77 

1724 

18.56 

1742 

18.36 

1761 

18.17 

1932 

16.57 

63 

1: 0.587 

1724 

18.56 

1745 

18.34 

1764 ! 

18.14 

1783 

17.95 

1961 

16.32 

64 

1: 0.563 

1745 

18.35 

1765 

18.12 

1786 

17.92 

1805 

17.72 

1992 

16.07 

65 

1: 0.538 

1765 

18.13 

1786 

17.91 | 

1808 

17.70 

1828 

17.50 

2023 

15.82 

66 

1: 0.515 

1786 

17.92 

1808 

17.69 I 

1830 

17.48 

1852 

17.28 

2054 

15.57 

67 

1: 0.493 

1808 

17.71 

1831 

17.47 

18 53 

17.26 

1876 

17.06 

208 8 

15.32 

68 

1: 0.471 

1830 

17.49 

1854 

17.26 

1877 

17.04 

1901 

16.83 

2123 

15.08 

69 

1: 0.449| 

1852 

17.28 

1878 

17.04 

1902 

16.82 

1927 

16.61 

2159, 

14.83 

70 

1: 0.429 

1875 

17.07 

1902 

16.83 

1926 

1 

16.60 

1953 

16.39 

2195 

14.58 


* 80 per cent pyrite and 20 per cent, quartz. 










































































Index 


PAGE 

Agitation of Sand and Slime . 37 

Agitation of Slime . 13 

Agitation Tanks. 52 

Akins Classifier . 40 

Akins-Kothwell Agitator . 52 

Amalgamation and Cyanide Plant . 32 

Announcement . 3 

Bullion Moulds . 03 

Classifiers .. . 40 

Clean Up . 23 

Concentration and Cyanide Plant .32,38 

Continuous Agitation .14, 53 

Continuous Decantation . 30 

Continuous Grinding Pans . 45 

Continuous Sand Leaching . 12 

Continuous Sand Washing..37,39 

Counter Current Method . 14 

Crushing Ore for Cvanidation . . 8 

Cyanide Process . 5 

Cyanides, Valuation of . 12 

Discharge Gates and Doors . 50 

Dissolution of Gold and Silver. 9 

Distributors for Sand Tanks. 48 

Doors, Discharge . 50 

Drawings of Cyanide Plants . 27 

Dry Crushing Cyanide Plant . 28 

El Oro Tube Mill Lining. 42 

Filter Bottoms for Tanks . 49 

Filters, Slime .5G, 58 

Filtration of Slime . 20 

Gates, Discharge .50,51 

Gate Valves . 51 

Grinding Pans . 45 

Ingot Moulds . G3 

Leaching and Percolation . ^ 

Leaching Tanks . ^4 

Lining, El Oro . 42 

Melting Precipitates . -3 

Mill Plans . 27 

Mills, Tube . 41 

Moulds, Bullion and Slagging . ^ 

Ore Testing . 2( ’ 

Pans, Grinding . 40 














































JUL 26 1912 


79 INDEX. COLORADO 

* " IRON WORKS CO 

PAGE 

Percolation and Leaching. 9 

Plans of Mills . 27 

Pneumatic Agitation . 13 

Portland Slime Filter . 5G 

Potassium Cyanide . 12 

Pouring Moulds . 63 

Precipitation Boxes .60-62 

Precipitation of Gold and Silver . 22 

Preliminary Tests . 26 

Preparation of Ore . 7 

Quick Opening Gate Valves . 51 

Refining of Precipitates . 23 

Repair Work . 4 

Rothwell Filter . 58 

Rothvvell Thickener . 54 

Rothwell-Lowden Method . 18 

Sand Distributors . 48 

Sand Leaching . 9 

Sand Tanks . 64 

Sand Washing, Continuous . 37,39 

Sand and Slime Agitation . 37 

Sand and Slime Classifiers . 46 

Shipping Directions . 4 

Slagging Moulds . 63 

Slime Filters .56-59 

Slime Thickening Tanks . 55 

Slime Treatment . 13 

Slimes, Separation of . 20 

Solution Tanks . 64 

Stamp Crushing Cyanide Plant . 32 

Tables .64-70 

Tailings Cyanide Plant . 39 

Tanks . 64 

Terms . 4 

Testing of Ores . 26 

Thickening Tanks . 54 

Tube Mills . 41 

Tube Mill Lining. 42 

Valves, Gate for Slime Tanks . 51 

Washing by Decantation . 30 

Washing of Sands, Continuous . 37,39 

Webb Agitation Tank . 13 

Zinc Boxes .60-62 

Zinc Precipitation . 22 


THE W. F. ROBINSON PRINTING CO. 



















































■ 









